IMAGE  EVALUATION 
TEST  TARGET  (MT-3) 


1.0 


I.I 


125 


■^■2.8 

u   lift    "^ 

[^  U&    12.0 

111 


11:25    III  1.4 


I 


1.6 


6" 


FiiotDgraphic 

^Sciences 

Carporation 


23  WIST  K^AIN  STREET 

WEBSTER,  N,Y.  145*0 

(716)  t7il-4S03 


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v.v 


,y(a 


HB 


CIHM/ICMH 

Microfiche 

Series. 


CIHM/rCMH 
Collection  de 
microfiches. 


Canadian  Institute  for  Historical  Microreproductions  /  Institut  Canadian  de  microreproductions  historiques 


Technical  and  Bibliographic  Notoa/Notaa  tachniquaa  at  bibliographiquoa 


t( 


Tha  Inatituta  haa  anamptad  to  obtain  tha  boat 
original  copy  availabia  for  filming.  Paaturoa  of  thia 
copy  which  may  ba  bibliographically  uniqua, 
which  may  altar  any  of  tha  imagaa  in  tha 
raproduction.  or  which  may  significantly  ehanga 
tha  uaual  mathod  of  filming,  ara  chackad  balow. 


□    Colourad  covara/ 
CouvartMra  da  coulaur 


pn   Covara  damagad/ 


D 


D 
D 


D 


Couvartura  andommagia 

Covara  raato^ad  and/or  taminatad/ 
Couvartura  raatauria  at/ou  palliculAa 


□   Covar  titta  miaaing/ 
La  titra  da  couvartura  manqua 

□   Colourad  mapa/ 
Cartaa  gAographiquaa  ^n 


D 


couMur 

Colourad  ink  (i.a.  othar  than  blua  or  black)/ 
Encra  da  coulaur  (i.a.  autra  qua  blaua  ou  noira) 

Colourad  piataa  and/or  illuatratiana/ 
Planchaa  at/ou  illuatrationa  •»  coulaur 


Bound  with  othar  matarial/ 
RalM  avac  d'autraa  doeumanta 

Tight  binding  may  cauaa  shadows  or  diatortion 
niong  intarior  margin/ 

Laraliura  sarrAa  paut  cauaar  da  I'ombra  ou  da  la 
diatoraion  ki  kmg  da  la  marga  intAriaui'O 

Blank  laavaa  addad  during  rastoration  may 
appaar  within  tha  taxt.  Whanavar  poaaibla.  tha?« 
hava  baan  omittad  from  filming/ 
II  sa  paut  qua  cartainaa  pagaa  blanchaa  ajoutias 
lors  d'una  raatauration  apparaiasant  dana  la  taxta, 
maia,  lorsqua  cala  Atait  poaaibla,  caa  pagaa  n'ont 
paa  M  film^aa. 

Additional  commanta:/ 
Commantairas  supplimantairas; 


L'Institut  a  microfilmi  la  maillaur  axamplaira 
qu'il  lui  a  iti  poaaibla  de  sa  procurer.  Laa  ditails 
da  cat  aitampiaira  qui  sont  paut-Atra  uniquaa  du 
point  da  vua  bibliographiqua.  qui  peuvant  modifiar 
una  imaga  raproduita.  ou  qui  pauvant  axigar  una 
modification  dana  la  mithoda  normala  da  filmaga 
sont  indiquAs  d-daaaoua. 


pn  Colourad  pavioa/ 


Q 


Pagaa  da  coukiur 

Pagaa  damagad/ 
Pagaa  andommagAaa 

Pagaa  raatorad  and/oi 

Pagaa  raatauriaa  at/ou  pallicul4aa 

Pagaa  diacolourad.  stainad  or  foxai 
Pagaa  dteoioriaa,  tachatias  ou  piquias 

Pagaa  datachad/ 
Pagaa  ditachAas 


r~~1  Pagaa  damagad/ 

rn  Pagaa  raatorad  and/or  laminatad/ 

ry]  Pagaa  diacolourad.  stainad  or  foxad/ 

rn  Pagaa  datachad/ 


|~n   Showthrough/ 


Transparanca 

Quality  of  prir 

QuaiitA  inAgakt  da  I'impraaaion 

Includaa  supplamantary  matarii 
Comprand  du  material  supplAmantaira 

Only  adition  availabia/ 
Sauia  Mition  diaponibia 


nn   Quality  of  print  variaa/ 

n~|   Includaa  supplamantary  matarial/ 

p~|   Only  adition  availabia/ 


T 

P 

o 
fi 


0 
b 
t» 
fi 
o 
fi 
ai 

01 


T 
al 

Tl 
v«i 

U 

: 

b( 

ril 
rs 
m 


Pagaa  wholly  or  partially  obscured  by  errata 
slips,  tissues,  etc..  have  been  ref limed  to 
ensrire  the  best  possible  image/ 
Lea  pagaa  totaiement  ou  partiallement 
obscurcies  par  un  feuillet  d'errata.  una  pelure. 
etc..  ont  it*  filmies  i  nouveau  de  faqon  A 
obtenir  !a  meilleure  imaga  possible. 


This  Item  is  filmed  at  the  reduction  ratio  checked  below/ 

Ce  document  e«t  filmA  au  taux  da  reduction  indiquA  ci*daaaoua. 


10X 

14X 

18X 

22X 

2BX 

»X 

y 

12X 


16X 


aox 


24X 


28X 


32X 


ils 
lu 

lificr 
n« 


Th«  copy  filmed  hw  has  h—n  raproducad  thanks 
to  tha  flanarosity  of: 

Library  of  tha  Pubiic 
Archivas  of  Canada 

Tha  imagas  appearing  hara  ara  tha  bast  quality 
possibia  eonaidaring  tha  condition  and  iagibiiity 
of  tha  original  copy  and  in  icaaping  with  tha 
filming  contract  spacif icationa. 


Original  copiaa  in  printad  papar  covars  ara  fllmad 
beginning  with  tha  front  covar  and  ending  on 
tha  last  page  with  a  printad  or  illuatratad  imprea- 
tion,  or  the  bacic  cover  when  eppropriata.  All 
other  original  copies  are  filmed  beginning  on  the 
first  page  with  a  printed  or  Illustrated  impres- 
sion, and  ending  on  the  last  page  with  a  printed 
or  illustrated  impression. 


The  last  recorded  frame  on  each  microfiche 
shall  contain  tha  symbol  — ^-  (meaning  "CON- 
TINUED"), or  tha  symbol  y  (meaning  "END"), 
whichever  applies. 


L'exemplaire  filmA  fut  reproduit  grfice  i  la 
gAnAroaitA  da: 

La  bibliothAqua  des  Archives 
pubiiques  du  Canada 

Las  Images  suivantas  ont  At*  raproduites  avac  la 
plua  grand  soin,  compta  tenu  de  la  condition  at 
da  la  nattetA  d»  I'exemplaire  film*,  et  en 
conformM  av«c  las  conditions  du  contrat  da 
filmrge. 

Lee  exempleires  origlnsux  dont  la  couvarture  en 
papier  eat  ImprlmAe  sent  filmfe  en  commentpant 
par  la  premier  plat  et  en  terminant  salt  par  la 
darnlAre  page  qdi  comporte  une  empreinte 
d'impresslon  ou  d'illustration,  soit  par  la  second 
plat,  salon  la  ces.  Tous  les  autras  exempleires 
origlneux  sent  filmte  an  commen^ant  par  la 
pramlAre  pege  qui  comporte  une  empreinte 
d'impreaaion  ou  d'illustration  at  an  terminant  par 
la  darnlAre  pege  qui  comporte  une  telle 
empreinte, 

Un  des  symboies  suivents  apparattra  sur  la 
darnlAre  image  de  cheque  microfiche,  seion  ie 
ces:  Ie  symbols  -^  signifie  "A  SUIVRE",  ie 
symbols  y  signifie  "FIN". 


IMaps,  plates,  charts,  etc.,  may  be  filmed  at 
different  reduction  retios.  Those  too  large  to  be 
entirely  included  in  one  exposure  are  filmed 
beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  es 
required.  The  following  diagrams  illustrate  the 
method: 


Les  certes,  planches,  tableeux,  etc.,  peuvent  Atre 
filmto  k  des  taux  da  rMuction  diffArents. 
Lorsque  Ie  document  est  trop  grsnd  pour  *tre 
reproduit  en  un  seul  clich4,  il  est  film*  A  partir 
da  I'angle  supArieur  gauche,  de  gauche  i  droite. 
et  de  haut  an  bas,  an  prenant  la  nombre 
d'imagas  nteessaira.  Les  diagrammes  suivents 
illustrent  Ie  mAthode. 


ita 


lure. 


] 


1 

2 

3 

1 

2 

3 

4 

5 

6 

.•^-mti. 


•J 


< 

G 


1 


ALBUM  OF  DESIGNS 


OK  TIIK 


PHCENIXVILLE   BRIDGE-WORKS. 


CLARKE,  REEVES  &  CO., 


OFFICE   No.  410  WALNUT    STREET, 


-«^ 


PHILADELPHIA. 


J.  B.  LIPPINCOTT  &   CO. 

PHILADELPHIA. 
1873. 


H- 


TiK 

Aui 

{1)11 


E] 


tc 

tl 
I 

o 

tl 

V 

1 
f 

e 

J 


Thomas  C.  Clakkk, 

AllULfHUS    DllNZANO, 

{CHIN  Gmi'mN, 
)AVI11    KliUVUS. 


PIKUNIXVILLR  HRIPGR-WORKS. 


Offich  of  CLARKE,   REEVES  &  CO., 

ENuINEERS,  CONTRACTORS,  AND  BUILDERS  OF  IRON  BRIDGES,  VIADUCTS,  ROOFS,  ETC. 

NO.   410  WALNUT    STREET,   ROOM    2. 

P.  O.  Lock  Box  No.  a.  p  JJ  J  I  ^  D  \l  L  P  H  J  A. 


In  presenting  our  second  circular,  we  take  occasion 
to  call  the  attention  of  our  friends  and  customers  to 
the  following  points: 

We  have  entered  into  contract  with  the  Phoenix 
Iron  Company,  Phoenixville,  Pa.,  for  a  long  term 
of  years,  by  which  that  Company  transfers  to  us  all 
their  iron  bridge-building,  and  orders  for  bridges  and 
viaducts  are  handed  to  us  for  execution. 

By  this  arrangement  the  whole  resources  of  the 
Phoenix  Iron  Company  can  be  concentrated  upon  tiie 
fulfdlment  of  our  orders.  Their  present  facilities  are 
equal  to  turning  out  o/zc  hundred  feet  of  finished  bridge 
for  eaeh  ivorkiitg  day  in  the  year,  and  can  be  increased, 
in  case  of  necessity. 

Everything  is  done  upon  the  premises;  beginning 
with  the  manufacture  of  the  iron  from  tlie  ore,  next 
rolling  it  into  the  sliapes  required,  and  finally  apply- 
ing the  machine-labor  that  completes  the  structure 
ready  for  erection.*  It  is  believed  that  all  this  is  done 
by  no  other  single  company  in  this  country. 

It  results  in  a  uniform  excellence  of  quality  of  iron 
and  workmanship,  which  cannot  be  got  from  bridge- 
builders  who  procure  their  iron  from  different  makers, 
and  generally  at  the  cheapest  rates. 

We  are  prepared  to  construct  any  style  of  wrought- 
iron  bridge,  and  according  to  any  specified  dimensions 
and  wciglits ;  at  the  same  time,  we  would  call  the  at- 
tention of  engineers  and  railway-men  to  that  style  of 
bridge  which  we  have  been  building  during  the  last 
five  years,  which  has  stood  the  test  of  use,  with  the 
marked  approbation  of  those  best  able  to  judge. 


'''  See  description  of  Pliojnix  Works,  illustrrtleil  by  woodcuts.     Ex- 
Iriictecl,  by  permission,  from  Lippiiuotl's  Mai;aziiie.    Appendix  No.  i. 


What  we  claim  as  the  peculiar  advantages  of  our 
bridges  are  as  follows  : 

We  use  that  style  of  truss  (originally  developed  in 
wood  by  Pratt  and  in  iron  by  Whipple)  which  expe- 
rience has  shown  to  be  the  best  adapted  for  railway 
purposes,  as  there  are  more  of  them  in  use  in  this 
country  than  of  any  other  kind. 

So  far  as  we  have  modified  the  connections  and  other 
details  of  construction,  we  have  endeavored  to  be  guided 
by  the  following  principles : 

Simplicity  and  uniformity  of  construction  ;  least  pos- 
sible exposure  of  surliice  to  corrosion ;  uniformity  of 
strain  on  all  parts  alike ;  concentration  of  material 
along  the  lines  of  strain ;  and  the  use  of  the  most  suit- 
able kind  of  material  for  tlie  purposes  required. 

At  the  request  of  many  railway-men,  we  have  pre- 
pared a  set  of  der>igns,  accompanied  by  detailed  speci- 
fications, covering  the  proportions  and  quality  of 
material  and  workmanship  under  which  they  will  be 
constructed. 

They  have  nearly  all  been  actually  built  by  us,  and 
have  borne  the  test  of  use.  Persons  requiring  bridges 
will  find  among  these  everything  they  want,  unless  for 
special  ca.ses,  for  which  we  will  prepare  special  plans 
and  estimates,  free  of  charge,  when  requested. 

We  build  our  short  spans  stronger  than  has  been 
heretofore  customary,  providing  for  a  variable  load  of 
two  tons  per  foot.  We  do  this,  because  there  is  gen- 
erally no  slackening  of  speed  in  crossing  a  short  span, 
and  the  live  load  of  the  locomotive  bears  a  much  greater 
proportion  to  the  lead-weighl  of  the  structure  in  short 
than  in  long  spans.  At  250  feet  span  the  live  and 
dead  loads  are  nearly  equal,  while  on  a  30-feet  span 
the  live  load  is  more  than  four  times  the  dead  load. 


PIUENIXVILLE  BRIDGE -WORKS. 


As  the  live  load  is  accompanied  with  imi)act  and  vibra- 
tion, and  foiir-fiftlis  of  the  strain  comes  from  it,  it  is 
but  prudent  to  taice  this  into  account.* 

In  i)roportioning  the  different  parts  of  our  bridges, 
the  strain  i)er  square  inch  is  diminished  ;  or  in  otlier 
words,  tiie  strength  of  each  part  is  increased  in  pro- 
portion to  its  nearness  to  its  work.  As  the  panel 
system  is  fully  strained  by  the  passage  of  each  locomo- 
tive, it  should  have  greater  strength  than  the  chord 
system,  which  can  only  get  its  maximum  strain  when 
the  whole  length  of  the  bridge  is  covered  with  loco- 
motives, which  in  practice  seldom  occurs  on  spans 
longer  than  loo  feet.  The  bolts  which  support  the 
floor  system,  being  subject  to  accidental  shocks,  have 
the  greatest  strength  of  all.  This  is  merely  follow- 
ing out  in  p.actice  the  principle  of  "uniformity  of 
strains."  Inasmuch  as  the  strength  of  an  iron  bridge 
(like  that  of  an  iron  chain)  is  measured  by  the  strength 
of  its  weakest  part,  it  follows  that  the  structure  in 
which  tiiis  principle  is  most  accurately  carried  out  will 
be  the  strongest,  while  the  purchasers  of  the  bridge 
will  not  be  compelled  to  pay  for  useless  iron,  which 
diminishes  instead  of  adding  to  its  strength.  On  the 
other  hand,  if  bridges  are  too  light,  they  will  show  this 
defect  by  excessive  vibration  under  a  passing  train. 
This  fault,  we  believe,  our  bridges  cannot  be  charge<l 
with.  We  furnish  diagrams  of  strains,  giving  the 
actual  dimensions  of  each  part,  and  the  calculated 
strains. 

We  have  given  fourteen  plates,  in  which  are  shown 
all  the  different  kinds  of  iron  bridges  occurring  in 
ordinary  practice.  Each  style  of  bridge  is  distin- 
guished by  a  letter  and  number. 

Persons  requiring  bridges  will  please  follow  the  fol- 
lowing directions : 

1.  Give  the  letter  and  number  o{  figure  for  the  gen- 
eral style  of  bridge  required,  and  the  length  of  spans 
between  centres  of  piers,  and  width  of  piers,  if  any  are 
built. 

2.  State  whether  the  bridge  is  at  right  angles  or  on 
a  skew.  If  the  latter,  give  the  angle  included  between 
line  of  piers  and  axis  of  bridge. 


3.  (live  the  height  of  bottom  of  rail  above  bed  of 
stream. 

4.  State  whether  the  railway  company  will  themselves 
builil  the  lower  staging  up  to  the  track-level,  or  not. 

5.  If  not,  give  the  depth  of  svater,  and  whether  the 
nature  of  the  bottom  recpiires  piles,  or  not. 

6.  If  a  viaduct  be  recpiired,  it  will  be  better  to  send  a 
( ross-section  of  the  valley,  indicating  such  points  as  re- 
(juire  a  fixed  length  of  span, — such  asstreams,  roads,  etc. 

If  railway  companies  prefer  to  erect  the  iron-work 
themselves,  we  will  furnish  a  competent  person  to 
superintend  the  erection,  and  guarantee  the  work 
coming  together  with  exactness.  It  will  generally  be 
found  more  satisfactory  that  we  should  erect  the  bridge 
and  lay  the  track  upon  it  ready  for  use,  the  company 
furnishing  ties  and  rails  and  the  timber  and  other 
materials  for  staging. 

With  the  above-mentioned  data  furnished,  we  can 
(juote  prices,  by  return  of  mail,  to  any  one  who  wants 
:  bridges,  and  can  construct  the  bridges  in  as  short  a 
I  time  as  any  other  bridge-builders  can  do.     We  wish 
it  particularly  understood  that  our  cash  rates  are  uni- 
form to  all  persons  alike;  modified  only  by  the  amount 
\  of  work  ordered.     We  can  always  execute  an  order  for 
a  number  of  bridges  for  a  less  price  each  than  for  a 
single  one,  on  account  of  the  reduplication  of  parts 
lessening  the  cost  of  manufacture,  and  the  less  cost  of 
erection,  for  various  obvious  reasons. 
j      We  will  make  special  plans  and  estimates  to  suit  any 
'  required  case,  but  wish  to  point  out  that  there  will  be 
a  marked  economy  insured,  both  in  cost  and  in  time, 
by  selecting  one  of  our  regular  styles  of  bridge,  as  per 
plan  and  si)ecification,  as  we  have  now  on  hand  a  large 
stock  of  dies   and  patterns  which  are  applicable  to 
them.* 
The   following   is  a  list  of  the   iron   railway  and 
'  other  bridges  and  viaducts  that  we  have  built,  or  are 
building,  since  our  connection  with  the  Phcenix  Iron 
!  Company ;  also,  of  the  railways  and  their  officers  for 
;  whom  they  were  built,  and  to  whom  we  would  respect- 
fully refer  parties  desirous  of  further  information  as  to 
I  our  capacity : 


*  See  extract  from  p.tper  read  before  Aineric.in  Society  of  Civil 
Engineers,  by  J.  Griffon  and  T.  C.  Clarke.    Appendix  No.  2. 


'  See  extract  from  Rai/roati  Gazi't/i,  describing  competition  for 
new  bridsjes  in  tlic  Dominion  of  Canada. 


VHiENlX  VILLE   BRJD  GE  -  WORKH. 


LIST  OF 

WROUGHT-IRON  BRIDGES  AND  VIADUCTS, 

BUILT  AND  NOW  BUILDING  BY 

CLARKE,  REEVES  &  CO., 

FROM  1869  TO  1873. 


I'OH    WIIUM    UUILI. 


WIIRKK    IIUILT. 


C.   H.  &Q 

ItlinuiK  Central  

ChiraKoft  N.  W 

I'liilad  ,  Wil.  &  llaliimori;. 


KcMiliiii;  K.  K 

llrid^cton,  N.  j 

Nurifi  Ptiiinsyfwini.i  R.  R.. 
U.  S.  ArHcn.il 


HurliiiKi'Mi,  Mo 

La  Salic,  111 

CMilltnll,  Inwa 

Chtislcr,  l*a.     J  Iracks 

•'        "  Draw,  i  Iracks 
Flowerti'wii 


NO.      LKNGMI. 


18 


I'urllandS:  Kl-hhuIio:  R  U 
Conn.  Air  Line  R.  R 


Hudson  River  llridyc  Co  . 


l'urtlandJini;duiisl)'r)jR  R 
Cambria  Iron  <    1 


llrid^eton.     IJraw 

Saiictm  Creek 

Rock  Island,  III.   Ilitjliway. 

AiiUUsla,  Me 

Viaduct 


Norili  I'ou.l 

Ilaileyville 

Saddle  Hill 

I'istoi  Factory 

I.yniau  Viadui-t,     j  tracks 
Rapallo 


.Mljauy.    -J  tracks.. 


North  Pennsylvania  R.  R.. 
Clics.  &  Ohio  R.  R 


Portland  S:  Ojjdensh'rg  R .  K 

Calawissa  R.  R 

Intercolonial  RaiUv.iy  Co,.., 


Whcclock  Hrid«e  Co., 
West  Hiestcr  R,  K.,. 


Hiram,  Me 

Johnstown 

Sauctni  Creek... 


L'oi'way 

i  Viaduct 

Miraniichi 

Risti);ouche 

'I'erre  Haute.     Highway., 
Ulen  Mills 


North  i*ennsylvania  R.  R  .,, 
Camden  .<!:  Amlioy  R.  R..,, 
Alc.v.  T.  Stewart 


Chcs.  &  Ohio  R.  R., 
Maine  Central  R,  R 


Washington  Station  . 

Hi);htstown 

r,ong  Island 

Greenbrier  River 

llnutswick.Me.. 


l&o 

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55 
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1112 

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185 

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110 

40 

65  J 

183 

85 


f3-5o) 
l-'-  47) 


-J.S.T 

-  751 
158 


£3 

'A 


133 

3880 

300 

308 

508 

8j 

55 

'.<5 

■54 

60U 


975 

5'. 
48 
ViO 

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56 

111 

2324 


roll    WHOM    UUll.T. 


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4 — I  >;)  I 
4—120  )' 
2— 13,  I 
2— iSfi.f)/ 


WillUli!    laiLT. 


Ches.  ft  Ohio  R.  R Rivanna  Creek 

S.  Schotield .M.inayunk,     Highway. 

Ohio  ft  .Miss.  R,  R (.lochran 

No,  u 


"  "  Medora 

"  "  Scoltvillc 

WestKork 

"  "  "Ik  SuKar 

"  "  Little  Siiijar 

Little  Wabash,, 

Grand  Trunk  R'wayofCau,  St.  Hyacinthe.. 

"  "  ..  I'.lack  River 

..  White  River... 


3756  ;l 


3480 


.85 

340 

248 

660 

•116 

226 

231. 


.  ,St.  Francis 

M:.>;oK 

,  Massawippi.... 
.  Ctiaticoku 

Island  I'oiui.... 
jN.  Stratford... 
.  Ammonousuc. 

,  (it^rhain  

,  \V.  Paris 

,  S.  Paris 

Mcchan's  Fall* 
.  N.  Vaniumth. 


Philad.,  Wil.Ct  Halt.  K.  R.  Ridley  Park. 


Rock  Isl.iiui  Ar>cnal 

Central  R.  R.  of  N.J 

Nurlh  Pennsylvania  k.  R 

(.lenevait  Ithaca  R.  R.... 


5" 
80 

129 

M9 

ij8 


Molinc.  III.. 
Panirapo. 

Sellersvillc . 


'ranylianock...  . 

SheUlr.ikc  t'err  ■ 
,  'IVninan^liuri' 
,  Senega  Car  il 


?  tracks 


Costa  Uica  Railway Costa  Rica, 

City  of  Pliiladclphia 


NO.     LCNGTIt. 


(    Cirard  Av.,  I'xi  feet  wide."! 

Seven  trusses.    I''tiiial  to  ^ 

(      six  railroad  tracks \ 


{:= 


(.-: 


97 
93 

M5 

■47 

"47  I 

163  J 

'77 

307 

>"3 
33 

93 

27) 


( I- 

1 1- 
( I- 

■(■- 


■154 1 

■73f 
■IS.) 

•M"i 
118 

"7 
■■7 

107 

i"7 
124 

■47 
■  38 


-63I 

96-3 

102 
104 

QOO 

88 

-.V3l 

-  68  I 

-  74  I 

-  16  I 

■97  I 
■37) 


97 
93 
•45 
•47 
310 

53' 
4^4 
I>3 

3-' 
y2 

37' 

■55 
232 

297 

■'■7 
"7 

107 

■■7 
'-■4 
'47 
■  38 
121 


94 
289 


lo» 

QOO 
88 


w 


GENERAL    SPECIFICATIONS, 

ACCOHDINO    TO  WHICH    THK 

DESIGNS  OF   CLARKE,    REEVES    &  CO.'S    BRIDGES, 

GIVEN    IN   THIS  CIRCULAR, 


m 
re 


ARE  PROPOSED  TO  BE  CONSTRUCTED. 


1.  These  structures  are  proportioned  to  sustain  the 
passage  of  the  heaviest  cars  and  engines  in  use,  for  coal, 
freight,  or  passenger  traffic,  at  a  speed  of  not  less  than 
thirty  miles  per  hour,  viz.  :  two  locomotives  coupled, 
weighing  thirty  tons  on  drivers,  in  space  of  twelve  feet; 
total  weight  of  engine  and  tender,  loaded,  sixty-five 
tons  each,  and  followed  by  the  heaviest  cars  in  use,  viz. ; 
loaded  coal  cars,  weighing  twenty  tons  each,  in  twenty 
two  feet.  The  iron-work  will  be  so  proportioned  tiiat 
the  above  loads,  in  addition  to  the  weights  of  the  slruo 
tures  themselves,  shall  not  strain  the  iron  over  10,000 
pounds  per  square  inch  tensile,  or  7500  pounils  per 
inch  shearing  strain,  and  reducing  the  strain  in  com- 
pression, in  proportion  to  the  ratio  of  length  to  diam- 
eter, by  Gordon's  formula. 

2.  The  iron  used  under  tensile  strains  shall  be  of 
tough  and  ductile  quality,  and  be  capable  of  sustaining 
the  following  tests : 

THCENIX  DOUlil.E  RICFINED  OR  "BEST  BE.SI"  IRON. 
ROUND  llAK.— li  INCHES  I,.amktKR  IIV  12  INCIIKS  I.ONC. 

Ultimalc  sircnglli,  5?,ooo  to  60,000  ll)s.  [jcr  s(|ii,uc  inch. 

No  perm.-ment  set  \indcr       25,000  to  30,000        "  " 

Reductimi  of  area  at  breaking  point,  average  25  per  cent. 

Elongation        "  "  "  "  i.5 

Cold  bend  witliont  signs  of  fractnre,  from  90  to  180  degrees. 


3.  All  workmanship  shall  be  first-class.  In  work 
having  pin  connections,  all  abutting  joints  shall  be 
planed  or  turned,  and  no  bars  of  wroiight-iron  having 
nn  error  of  over  i-64th  of  an  inch  in  length  between 
pin-holes,  or  over  i-iooth  of  diameter  of  pin  or  hole, 
shall  be  allowed.  In  riveted  work,  all  plates  and  joint 
plates  shall  be  square  and  truly  dressed,  so  as  to  form 
close  joints.  Rivet  holes  shall  be  spaced  accurately 
and  truly  opposite.  Rivets  shall  be  of  the  best  quality 
of  rivet  iron,  shall  completely  fill  the  holes,  and  shall 
have  full  heads. 

Chord-links,  main  ties,  and  suspension  bolts,  shall 
be  die-forged  without  welds.  Screw-bars  shall  have 
threads  enlarged  beyond  diameter  of  bar,  and  shall  be 
fitted  with  radial  nuts  anil  washers. 

All  liars  subject  to  tensile  strains  may  be  tested  to 
20,000  pounds  per  square  inch,  and  struck  a  smart  blow 
witli  a  hammer  while  under  tension  ;  and  if  any  show 
signs  of  imperfection  they  shall  be  rejected. 

All  the  iron -work  shall  be  painted,  before  leaving  the 
Works,  with  one  coat  of  metallic  paint  and  oil.  All 
machine-cut  work  shall  be  covered  with  white  lead  and 
tallow  before  leaving  the  Works. 

4.  These  bridges  shall  not  deflect,  under  the  passage 
of  a  train  of  locomotives  moving  at  thirty  miles  per 
hour,  over  i-i  200th  of  their  length,  and  shall  return  to 
their  original  camber  after  the  passage  of  the  train. 


(4) 


DKSCRIPTION    OF    PLATBS. 


I 


PLATE    Wo.    1. 

Desic.n  a — Figs.  I,  2,  3,  show  i\  simple  form  of 
girder  bridge  intended  for  spans  of  25  feet  and  under. 

It  consists  of  two  pair  of  rolled  Phcenix  beams,  of 
13  or  15  inches  deep,  according  to  span,  braced  to- 
gether and  resting  on  (ast-iron  i)lates. 

Where  the  headway  is  extremely  limited  the  arrange- 
ment sliown  in  cross-section,  Fig.  4,  may  be  iised,  which 
requires  a  depth  below  bottom  of  rail  of  but  11  inches. 

PLATE    No.   2. 
DKSKiN  H  is  a  trussed  girder  with  two  panels,  in- 
tended for  spans  of  25  to  30  feet,  where  there  is  suffi- 
cient depth  below  the  rail  to  truss  the  beams  in  the 

manner  shown. 

PLATE    No.  3. 

Desr;n  C  show's  a  trussed  girder  with  more  than  two 

panels,  suited  for  si)ans  of  30  to  75  feet. 

PLATE    No.   /». 

Ukskin  D. — For  longer  spans  than  75  feet  we  use  our 
regular  pattern  of  deck  bridge,  with  top  choi  Is  and 
posts  made  of  Piuenix  columns,  and  having  side  cross 
floor-l)eams.  The  track  stringers  can  be  either  of  wood, 
as  shown  in  the  plate,  or  of  iron,  if  specially  ordered. 

Where  jireferred,  the  tojjs  of  masonry  piers  need  not 
be  carried  above  the  bottom  chords  of  the  iron  truss, 
and  the  level  of  bridge  seat  at  abutments  will  be  the 
same.  In  this  case  the  ends  of  the  iron  trusses  will  be 
supported  on  vertical  Phcjenix  columns. 

PLATE    No.   5. 

This  plate  shows  the  details  of  construction  of  the 
deik  bridge  illustrated  in  Design  1),  J'late  No.  4. 

PLATE  No.  6. 
Design  E. — This  plan  of  what  is  sometimes  called  a 
"  pony"  truss  bridge  is  used  for  through  bridges,  where 
the 'depth  below  rail  is  somewhat  limited,  in  spans  of 
from  30  to  60  feet,  and  may  be  carried  up  to  80  feet  at 
points  where  it  is  desirable  to  give  the  engineer  an  un- 
obstructed view  over  the  tops  of  the  trusses.  We  pre- 
fer, however,  at  60  feet  span  to  carry  up  the  trusses  and 
brace  them  overhead. 

PLATE    No.   7. 

Design  F. — 'L'iiis  is  our  regular  pattern  of  through 

bridge.    18  feet  and  upwards  in  clear  height,  and  14  feet 

in  clear  width  for  single  track.     For  doui)le  track  we 

recommend  two  trusses,  with  a  clear  width  of  26  feet. 

PLATE    No.   8. 
This  shows  the  details  of  construction  of  the  through 
bridges  shown  .n  designs  E,  F,  and  the  highway  bridge 
design  G,  Plate  No.  11. 


PLATE    No.   9. 

Desion  H This  is  our  regular  pattern  of  through 

pivot- bridges,  with  our  patent  turn-table,  of  a  simple 
and  effective  construction.  Where  a  pivot-pier  has  to 
be  specially  construe  ted,  considerable  economy  will  be 
obtained  by  carrying  uj)  a  circular  wall  of  masonry,  and 
reducing  the  dei)th  of  iron  ring,  as  shown  in  Fig.  35. 
Our  [livot-bridges  have  always  given  satisfaction  ;  and 
we  refer  particularly  to  that  over  the  Hudson  River 
at  Albany,  belonging  to  the  New  York  Central  and 
Hudson,  and  the  Boston  and  .Albany  Railroads, 
as  a  model  of  a  quick-working  and  substantial  pivot- 
bridge. 

PLATE    No.   10. 

This  plate  shows  the  details  of  our  patent  locking 
and  self-centring  arrangement  for  pivot-bridges,  the 
operation  of  which  will  be  best  understood  by  the 
description  of  the  patent  itself,  dated  June  i8,  1872. 

IMPROVEMENTS  IN  PIVOT-BRIDGES. 

Our  invention  relates  to  certain  improvements  in  pivot- 
bridges,  too  fully  explained  hereafter  to  need  preliminary 
description  ;  the  said  improvements  having  jr  their  object, 
first,  the  ready  withdrawal  of  the  corner-sui)ports  of  the 
bridge,  when  the  latter  has  to  be  turned  on  its  pivot,  and 
the  ready  restoration  of  these  supports  when  the  positior  of 
the  bridge  demands  them  ;  and  second,  the  self-centiing 
of  the  bridge,  so  that  the  nice  and  tedious  manipulative  ad- 
justment demanded,  in  order  that  the  rails  of  the  bridge 
may  coincide  with  those  of  the  permaneni  track,  is  rendered 
unnecessary. 

In  the  accottipanying  drawing,  Fig.  37  is  a  view  of  a 
portion  of  the  end  of  a  pivot-tiridgc ;  Fig.  36,  a  side  view 
of  a  portion  of  one  end  of  the  bridge ;  Fig.  38,  a  plan  view 
of  Fig.  I  ;  and  Fig.  39,  a  perspective  view  illustrating  a  part 
of  our  invention. 

A  and  A'  are  two  transverse  beams  at  one  end  of  the 
bridge  ;  these,  together  with  other  transverse  beams  of  like 
character,  supporting  the  longitudinal  beams  B,  across 
which  extend  the  ties  D  for  receiving  the  rails  tt  a.  The 
transverse  beams  A  p.re  secured  to  the  lower  chord-beams 
by  suspension-bolts  i\  this  lower  chord  forming  part  of  a 
truss-frame  of  which  the  pivot-bridge  is  composed,  and  of 
which  F  represents  a  portion  of  one  of  the  diagonal  end 
posts.  To  the  transverse  beam  A  are  hung,  by  means  of 
a  pin  /,  a  series  of  links  /'  /'  /  /,  and  to  the  latter  are  hung, 
by  means  of  a  pin  J,  a  series  of  similar  links  w,  and  to  a 
pin  passing  through  the  lower  ends  of  the  latter  series  of 
links  are  hung  two  rollers,  //,  which  are  guided  vertically 
by  brackets  ^  y,  secured  to  the  under  side  of  the  beams  A. 
The  two  sets  of  links,  as  will  be  seen  hereafter,  form  a  knee- 
joint  to  the  central  piny,  of  which  two  rods,  GG,  are  jointed, 
the  opposite  ends  of  these  rods  being  connected  to  the  lower 
ends  of  arms  H,  which  are  hung  to  the  transverse  beams 
A  A,  and  these  arms  are  connected,  by  a  rod,  I,  to  lugs  on 
a  nut  J,  which  is  adapted  to  vertical  guides  arranged  be- 
tween the  two  beams  A  A,  the  said  nut  being  also  connected 
by  similar  appliances  to  knee-joint  links  arranged  at  the 
opposite  corner  of  the  bridge,  which  is  not  shown  in  the 
drawing.    The  nut  J  is  controlled  by  a  vertical  screw,  so 

(S) 


DESCRIPTION   OF  PLATES. 


confined  to  suitable  bearings  //,  ser-  ed  to  the  beams  A  A, 
that  while  it  can  be  turned  easily  it  is  incapable  of  vertical 
movement.  This  screw  may  be  operated  by  any  suitable 
mechanism,  but  we  picfer  to  operate  it  from  a  central  point 
on  the  pivot-bridfje,  and  to  connect  the  ojierating  mechan- 
ism by  means  of  a  horizontal  shaft  extending  along  the 
bridge  beneath  the  ties,  one  end  of  the  shaft  being  geared 
by  bevel-wheels  to  the  screw  K  at  one  end  of  the  bridge, 
and  the  opposite  end  to  a  similar  screw  at  the  opposite  end 
of  the  bridge,  so  that  the  knee-joint  links,  at  r.li  four  corners 
of  the  bridge,  may  be  operaii;d  simultaneously  from  one 
point.  The  outer  ends  of  the  rails  a  ii,  at  each  end  of  the 
bridge,  admit  of  being  raised  and  lowered  by  the  same 
mechanism  which  operates  the  knee-joints.  Thus  the  rails 
rt  a,  in  Fig.  i,  are  connected  by  rods  jj  to  the  rods  I  l.and 
these  rails  are  adapted  to  chairs  (i  d,  which  are  secured  to 
the  permanent  roadway  or  permanent  part  of  a  bridge,  and 
which  receive  the  ends  of  the  permanent  rails  b  b  of  the 
track,  the  chair  thus  insuring  the  coincidence  of  the  rails 
of  the  pivot-bridge  with  those  of  the  permanent  track. 

As  seen  in  the  drawing,  the  bridge  is  supposed  to  be 
closed,  and  free  for  the  passage  of  trains,  the  rollers  /  at 
the  lower  end  of  the  knee-jointed  links  at  each  corner  of 
the  bridge  bearing  in  a  cavity  in  the  top  of  a  plate  /, 
secured  to  the  foundation  or  pier ;  and,  the  pins  of  the  knee- 
joint  links  being  in  the  same  vertical  line,  the  links  afford 
a  steady  support  for  the  bridge  at  each  of  its  four  corners. 
When  it  is  necessary  to  swing  the  bridg?  round,  the  screw 
K,  at  each  end  of  the  bridge,  is  turned  so  as  to  elevate  the 
nuts  J.  This  consequently  draws  the  rods  G  and  1  in  the 
direction  of  the  arrows,  and  therefore  so  acts  on  the  knee- 
joint  links  as  to  elevate  the  rollers//  in  their  guides  ;  and 
tl'.is  is  continued  until  the  bridge  is  in  the  tirst  instance 
lowered  and  supported  on  its  centre  jjivot  only,  and  after- 
ward until  the  rollers  are  clear  of  their  bearings.  Simul- 
taneously with  this  movement  of  the  knee-joint  links,  the 
outer  ends  of  the  rails,  owing  to  iheir  connections  with  the 
rods  1  I,  were  elevated  clear  of  the  chairs  d  d,  as  seen  in 
Fig.  4,  and  conseciucntly  the  bridge  is  free  to  be  turned  on 
its  pivot.  In  restoring  the  bridge  to  its  original  position, 
it  is  turned  round  until  the  rollers  //of  the  knee-joint 
links  are  above  tl^c  cavity  of  the  foundation-plate  /.  It  is 
very  rarely,  however,  that  tiie  bridge  can  be  arrested  in  its 
movement  at  a  point  where  the  said  rollers  are  directly 
above  the  centre  of  the  said  cavity  ;  but  as  soon  as  tlie 
screws  K  are  operated  to  straighten  the  knee-joint  links, 
and  the  rollers  q  begin  to  bear  upon  the  plrtes  /,  the  weight 
on  r.ie  rolleis  will  induce  them  to  descend  into  the  cavities 
of  the  plates,  and  hence,  as  the  straightening  of  the  knee- 
joints  is  continued,  the  bridge  will  be  slightly  turned,  until* 
the  rollers  have  r.rrived  at  the  most  depressed  portion  of 
the  cavities  ir,  tlie  plates,  and  there  remain  while  the 
st.;i'.ghtcning  of  the  knee-jointed  links  is  continued  until 
their  pin^  are  in  the  same  vertical  line,  as  shown  in  Fig.  i. 
.\ftcr  the  bridge  had  adjusted  itself  in  the  manner  described 
duiing  the  picliminary  straightening  of  the  links,  and  this 
straightening  was  continued,  the  rails  a  a  on  the  bridge 
descended  until  they  rested  in  and  were  contined  laterally 
by  the  shoes  d  d  of  the  pen  lanent  track.  It  will  be  seen, 
therefore,  that  by  connecting  these  rails  ati  to  the  mechan- 
ism which  operates  the  knee-joints,  the  said  rails  are  ele- 
vated out  of  the  chair  simultaneously  with  the  releasing  ot 
the  bridge  from  its  corner-bearings,  and  when  the  knee- 
joints  become  the  corner-bearings  the  rails  are  lowered 
into  the  '  hairs,  and  their  coincidence  with  the  rails  of  the 
permanent  track  is  thereby  insured.  The  accidents  which 
have  frei[uently  occurred  through  the  non-coinciding  of 
the  rails  of  a  pivot-bridge  with  those  of  the  ijerm.incnt 
trajk  are  thus  prevented. 

The  knee-joint  bearings  at  the  corner  of  the  bridge  pos- 
sess this  important  advantage,  that  they  can  be  operated 
with  com|)aratively  little  exertion,  either  through  the  me- 
dium of  the  mechanism  described  or  any  equivalent  oper- 
ating devices. 


Although  wo  have  shown  and  described  a  pivot-bridge 
constructed  in  a  manner  which  we  deem  most  appropriate, 
it  should  be  understood  that  our  improvements  arc  appli- 
cable to  any  pivot-bridge.  A  change  in  the  operating 
mechanism  may  be  demanded  in  a  l)ridge  constructed  in 
a  manner  ditTering  from  that  described,  but  the  principal 
features  may  remain  ;  these  features  l)eing  the  knee-joint 
links,  forming  corner-supports  which  can  be  easily  with- 
drawn, and  ;'ie  plates  /,  'vhich  lender  the  bridge  self- 
centring. 

We  claim  as  our  invention — 

1.  The  combination,  with  a  pivot-bridge  substantially  as 
described,  of  knee-joini  supports  and  the  mechanism  de- 
scribed, or  any  equivalent  to  the  same,  for  operating  the 
said  joints. 

2.  In  combination  with  a  pivot-bridge  having  movable 
links  as  supports,  we  claim  plates  /,  constructed,  substan- 
tially as  described,  so  as  to  render  tiie  bridge  self-centring. 

PLATE  No.  11. 
De.sign  G. — This  is  our  usual  jjattern  of  highway 
bridge,  with  floor  l)cams  of  iron,  which  may  or  may 
not  be  trussed,  according  to  the  available  depth  below 
roadway.  It  is  constructed  exactly  like  a  railway 
bridge,  except  in  the  floor  system,  and  is  calculated  to 
su.itain  a  load  of  from  1500  to  2500  pounds  jjer  lineal 
foot,  witli  a  f''''tion  of  safety  of  5.  Teams  may  cross 
these  bridges  at  full  speed  without  doing  any  mischief. 

PLATE    No.    12. 

Design  I  is  an  iron  highway  bridge-,  'a>  be  used  for 
roads  crossing  over  railways.  Fig.  45  is  intended  for 
points  where  abutments  are  already  built,  or  where, 
from  the  railway  being  on  a  curve,  it  is  not  desirai)ie 
to  obstruct  the  view.  On  the  right  side  of  Fig.  45  a 
more  econo'viicai  construction  than  the  ordinary  stone 
abutment  is  suggested. 

PLATE    No.    13. 

Design  K  shows  our  method  of  constructing  wrought- 
iron  piers  for  bridges,  viaducts,  etc.  Tiiey  are  made 
of  four  Phoenix  columns,  braced  together  as  shown,  and 
secured  at  the  joints  by  our  i)atent  system  of  connec- 
tions. 

As  tlie  lengths  and  weights  of  spans  increase,  we  in- 
crease the  dimensions  of  the  columns  and  braces,  but 
t!ie  same  ^;eneral  form  of  construction  is  followed  for 
all  lengths  of  spans. 

PLATE    N(j.    14. 

De,sI(;n  I,  shows  a  bridge  on  iron  [liers,  intended  for 
I'.ie  crossing  of  a  smail  stream  or  road,  where  good 
stone  foi  masonry  cannot  easily  be  got.  The  jjiers  can 
be  biiiit  of  s])lit  bouldeis,  or  of  concrete,  if  stone 
cannot  be  had;  and,  as  they  are  biirieil  in  the  embank- 
ments, concrete  will  answer  as  well  as  stone,  'i'hese 
piers  can  be  coped  with  stone  or  iron. 

Design  M  shows  a  wrought-iron  viaduct  resting  on 
cast-iron  screw  piies,  and  suitable  for  crossing  the  wide 
river  bottoms  of  the  western  and  southern  States,  where 
stone  is  scarce,  anil  where  a  wide  water-way  oust  be 
permanently  maintained. 


APPENDIX    No.   1. 


PH(ENIXVILLE  BRIDGE -WORKS. 


REPRINTED  FROM  LirPLXCOTTS  MAGAZINE  FOR    JANUARY,   1873. 


*'assi:miu.iN( 


iin.i;  i:ni)I;k  siii:i». 


In  a  grave). ml  in  Watcrtown,  a  village  near  Boston, 
M.iss.iihusetts,  there  is  a  tombstone  (  immemorating 
the  claims  of  the  departed  worthy  who  lies  below  to 
the  eternal  gratitude  of  posterity.  The  inscription  is 
dated  in  the  early  part  of  this  century  (about  iSio), 
but  the  name  of  him  who  was  thus  immortalized  has 
f.ided  like  the  date  of  his  deatli  from  my  memory,  while 
tlie  deed  for  which  he  was  distinguislied,  and  which 
was  re(  orded  upon  his  tombstone,  remains  clear.  "  He 
built  the  fimious  bridge  over  the  Charles  River  in  this 
town,"  says  the  record.  Tiie  diaries  Ri\er  is  here  a 
small  stream,  about  twenty  to  thirt\-  feet  wide,  and  the 
bridge  was  a  simple  wooden  structure. 

Doubtless  in  its  day  this  structure  was  considered  an 
engineering  feat  woi  thy  of  such  ])osthumous  immortality 
as  is  gained  by  an  epitaph,  anel  afforded  such  conveni- 
ence for  transportation  as  was  neetletl  by  the  commer- 
cial activity'  of  that  era.  From  that  time,  however,  to 
this,  the  ( hangcs  which  have  occurred  in  our  commer- 
cial and  industrial  metliods  are  so  fully  indicated  by 


I  the  changes  of  our  manner  and  method  of  bridge-build- 
ing that  it  .vill  not  be  a  loss  of  time  to  investigate  the 

\  present  condition  of  our  abilities  in  this  most  useful 

I  branch  of  engineering  skill. 

In  the  usual  archiTiological  classification  of  eras  the 
Stone  Age  precedes  that  of  Iron,  and  in  the  history  of 
bridge-building  the  same  secjuence  has  been  preserveil. 
Though  the  knowledge  of  working  iron  was  acquired 
by  many  nations  at  a  ]ire-historic  period,  yet  in  quite 
modern  times — witiiin  tliis  century,  even — the  inven- 
ion  of  new  processes  and  the  experience  gained  of 
new  methods  have  so  completely  revolutionized  this 
branch  of  industry,  anil  given  us  such  a  mastery  over 
this  material,  enabling  us  to  apply  it  to  such  new  uses, 
that  for  the  future  the  real  Age  of  Iron  will  date  from 
the  i)resent  century. 

The  knowledge  of  the  arch  as  a  method  of  construc- 
tion with  stone  or  brick — both  of  them  materials  aptly 
fitted  for  resistance  under  pressure,  but  of  comparatively 
no  tensile  strength — enabled  the  Romans  to  surpass  all 

(7) 


PHCENIXVILLE  BRIDGE-  WORKS, 


nations  that  had  preceded  them  in  the  course  of  his- 
tory, in  building  bridges.  The  bridge  across  the  Dan- 
ube, erected  by  Apoiiodorus,  the  architect  of  Trajan's 
Cohunn,  was  Vhe  largest  bridge  built  by  the  Romans. 
It  was  more  than  three  hundred  feet  in  height,  com- 
posed of  twenty-one  arches  resting  upon  twenty  piers, 
and  was  about  eight  hundred  feet  in  length.     It  was 


after  a  few  years  destroyed  by  the  emperor  Adrian,  lest 
it  should  afford  a  means  of  passage  to  the  barbarians, 
and  its  ruins  are  still  to  be  seen  in  Lower  Hungary. 

With  the  advent  of  railroads,  bridge-building  became 
even  a  greater  necessity  than  it  had  ever  been  before, 
and  the  use  of  iron  has  enabled  engineers  to  grapple 
with  and  overcome  difficulties  which  only  fifty  years 


THE    LYMAN   VIAUUL T. 


ago  would  have  been  considered  hopelessly  insurmount- 
able. In  this  modern  use  of  iron  advantage  is  taken 
of  its  great  tensile  strength,  and  many  iron  bridges, 
over  which  enormous  trains  of  heavily-loaded  cars  pass 
hourly,  look  as  though  they  were  spun  from  gossamer 
threads,  and  yet  are  stronger  than  any  structure  of  wood 
or  stone  would  be. 

Another  great  advantage  of  an  iron  bridge  over  one 
constructed  of  wood  or  stone  is  the  greater  ease  with 
wh!  jh  it  can,  in  every  part  of  it,  be  constantly  observed, 
and  every  foiling  part  replaced.  Whatever  material 
may  be  used,  every  edifice  is  always  subject  to  the 
slow  disintegrating  influence  of  time  and  the  e.-ments. 
In  every  such  edifice  as  a  bridge,  use  is  a  ]  ocess  of 
constant  weakening,  which,  if  not  as  constant!  guarded 
against,  must  inevitably,  in  time,  lead  to  its  destruction. 

In  a  wooden  or  stone  bridge  a  beam  affected  by  dry 
rot  or  a  stone  weakened  by  the  efi'ects  of  frost  may  l'-; 
hidden  from  the  inspection  of  even  the  most  vigilant 
observer  until,  when  the  process  has  gone  far  enough, 
the  bridge  suddenly  gives  way  under  a  not   unusual 


strain,  and  death  and  disaster  shock  the  community 
into  a  sense  of  the  inherent  defects  of  these  materials 
for  such  structures. 

The  introduction  of  the  railroad,  has  brought  about 
also  another  change  in  the  bridge-building  of  modern 
times,  compared  with  that  of  all  the  ages  which  have 
preceded  this  nineteenth  century.  The  chief  bridges 
of  ancient  times  were  bui!.;  uj  great  public  conveniences, 
upon  thoi  (highways  over  which  there  was  a  large  amount 
of  travel,  and  consequently  were  near  the  cif'es  or  com- 
mercial centres  which  attracted  such  travel,  and  were 
therefore  placed  where  they  were  seen  by  great  num- 
bers. Now,  however,  the  connection  between  the 
chief  commercial  centres  is  made  by  the  railroads,  and 
these  penetrate  immense  distances,  through  compara- 
tively unsettled  districts,  in  order  to  bring  about  the 
needed  distribution;  and  in  consequence  many  of  the 
great  railroad  bridges  are  built  in  the  most  unfrequented 
spots,  and  are  unseen  by  the  numerous  passengers  who 
traverse  them,  ur:onscious  that  they  are  thus  easily 
passing  over  specimens  of  engineering  skill  which  sur- 


PHCENIXVILLE  BRIDGE-WORKS. 


,  lest 
rians, 

T- 

came 
efore, 
rapple 

years 


pass,  as  objects  of  intelligent  interest,  many  of  the  sights 

they  may  be  traveling  to  see. 
The  various  processes  by  which  the  iron  is  prepared 

to  be  used  in  bridge-building  are  many  of  them  as  new 

as  is  the  use  of  this 
material  for  this 
prrpose,  and  it  will 


nLAST-Fl'RNACr.S. 


not  be  amiss  to  spend  a  few  moments  in  examining  them 

before  presenting  to  our  readers  illustrations  of  some  of 

the  most  remarkable  structures  of  this  kind.     Taking  a 

train  by  the  Reading  Railroad  from  Philadelphia,  we 

arrive,    in    about    an    hour,    at 

Phcenixville,    in    the  Schuylkill 

Valley,  where  the  Phoenix  Iron- 

and  Bridge-Works  are  situated. 

In    this    establishment   we    can 

follow  the  iron  from  its  original 

condition  of  ore  to  a    finished 

bridge ;    and  it   is  the  only  es- 

tablisliment  in  this  country,  and 

most    probably    in    the    world, 

wliere  this  can  be  seen. 

These  works  were  established 
in  1790.  In  1827  they  came 
into  the  possession  of  the  late 
David  Reeves,  who  by  his  en- 
ergy and    enterprise    increased 

their  capacity  to  meet  the  growing  demands  of  the 
time,  until  they  reached  their  present  extent,  employ- 
ing constantly  over  fifteen  hundred  hands. 

The  first  process  is  melting  the  ore  in  the  blast- 
furnace. Here  the  ore,  with  coal  and  a  flux  of  lime- 
stone, is  piled  in  and  subjected  to  the  heat  of  the  fires. 


driven  by  a  hot  blast  and  kept  burning  night  and  day. 
The  iron,  as  it  becomes  melted,  flows  to  the  bottom 
of  the  furnace,  and  is  drawn  off  below  in  a  gloiving 
stream.  Into  the  top  of  the  blast-furnaces  the  ore  and 
coal  are  dumped,  having  been  raised  to  the  top  by  an 
elevator  worked  by  a  blast  of  air.  It  is  curious  to 
notice  how  slowly  the  experience  was  gathered  from 
which  has  resulted  the  ability  to  work  iron  as  it  is  done 
here.  Though  even  at  the  first  settlement  of  this  coun- 
try the  forests  of  England  had  been  so  much  thinned  by 
their  consumption  in  the  form  of  charcoal  in  her  iron 
industry  as  to  make  a  demand  for  timber  from  this 
country  a  flourishing  trade  for  the 
new  settlers,  yet  it  was  not  until 
161 2  that  a  patent  was  granted  to 
Simon  Sturtevant  for  smelting  iron 
by  the  consumption  of  bituminous 
coal.  Another  patent  for  the  same 
invention  was  granted  to  John 
Ravenson  the  next  year,  and  in 
1619  another  to  Lord  Dudley; 
yet  the  process  did  not  come  into 
general  use  jntil  nearly  a  hundred 
years  later. 

The  blast  for  the  furnace  is 
driven  by  two  enormous  engines, 
each  of  three  hundred  horse-power. 
The  blast  used  here  is,  as  we  have 
said,  a  hot  one,  the  air  being  heated  by  the  consumption 
ofthe  gases  evolved  from  the  material  itself.  The  gradual 
steps  by  which  these  successive  modifications  were  intro- 
duced are  an  evidence  of  how  slowly  industrial  processes 


nUMPlNC.   OKK    AND    COAI.    INTO    llI.AST-Fl'RNACKS. 


1..V  '-"^n  perfected  by  the  collective  experience  of  gene- 
rations, and  show  us  how  much  we  of  the  present  day  owe 
to  our  predecessors.  From  the  earliest  times,  as  among 
the  native  smiths  of  .Vfrica  to-day,  the  blast  of  a  bellows 
has  been  used  in  working  iron  to  increase  the  heat  ofthe 
combustion  by  a  more  plentiful  supply  of  oxygen.   The 


10 


PHCENIXVILLE  BRIDGE-  WORKS. 


liLKVATlJK. 


blast-furnace  is  supposed  to  have  been  first  used  in  Bel- 
gium, and  to  have  been  introduced  into  England  in 
1558.  Next  came  the  use  of  bituminons  coal,  urged 
with  a  blast  of  cold  air.    But  it  was  not  until  1829  that 

Neilson,  an 
Englishman, 
conceived  the 
idea  of  heating 
the  air  of  the 
blast,  and  car- 
ried it  out  at 
t  h  e  Muirkirk 
furnaces.  I  n 
that  year  he 
obtained  a 
l)atent  for  this 
process,  a  n  d 
found  that  he 
could  from  the 
same  quantity 
of  fi'*'  make 
three  times  as  much  iron.  His  patent  mad  •"''•  <itxy 
rich :  in  one  single  case  of  infringement  he  received  a 
cheque  for  damages  for  one  hundred  and  fifty  thousand 
pounds.  In  his  method,  however,  he  used  an  extra 
fire  for  heating  the  air  of  his  blast.  In  1837  the  idea 
of  heating  the  air  for 
the  blast  by  the  gases 
generated  in  the  pro- 
cess was  first  practically 
introduced  by  M.  Fa- 
ber  Dufour  at  Wasser- 
alfilgen  in  the  kingdom 
of  Wiirtemburg. 

Ip  this  country,  char- 
coal was  at  first  used 
universally  for  smelting 
iron,  anthracite  coal 
being  considered  unfit 
for  the  purpose.  In 
1820  an  unsuccessful 
attempt  to  use  it  was 
made  at  Mauch  Chunk. 
In  1833,  Frederick  W. 
Geisenhainer  of  Schuyl- 
kill obtained  a  patent 
for  the  use  of  the  hot 
blast   with    anthracite, 

and  in  1835  produced  the  first  iron  made  with  this  pro- 
cess. In  1841  C.  E.  Detmold  adapted  the  consumption 
of  the  gases  produced  by  the  smelting  to  the  use  of 
anthracite;  and  since  then  it  has  become  quite  general, 
and  has  caused  an  almost  incalculable  saving  to  the 
community  in  the  price  of  iron. 


IIINNINC;    METAl.    INTO   PUIS. 


THK    iiN(iINl:-Kt)C>M. 


The  view  of  the  engines  which  pump  the  blast  will 
give  an  idea  of  the  immense  power  which  the  Phcenix 
company  has  at  command.  Twice  every  day  the  fur- 
nace is  tapped,  and  the  stream  of  liquid  iron  flows  out 
into  moulds 
formed  in  the 
sand,  making 
the  iron  into 
pigs  —  so 
calleil  from  a 
fancied  resem- 
blance to  the 
form  of  these 
animals.  'I'his 
makes  the  first 
proce.ss,  and 
in  many  smelt- 
ing establish- 
mei.cs  this  is 
all  that  is 
done,  the  iron 
in  this  form  being  sold  and  entering  into  the  general 
consumption. 

The  next  i)rocess  is  "boiling,"  which  is  a  modifica- 
tion of  "puddling,"  and  is  generally  used  in  the  best 
iron-works  in  this  country.     The  process  of  puddling 

was  invented  by  Henry 
Cort,  an  Englishman, 
and  patented  by  him  in 
1783  and  1784,  as  a 
new  process  for  ' '  shing- 
ling, welding,  and  man- 
ufacturing iron  and  steel 
into  bars,  plates,  and 
rods  of  purer  quality 
and  in  larger  quantity 
than  heretofore,  by  a 
more  effectual  applica- 
tion of  fire  and  ma- 
chinery." For  this 
invention  Cort  has  been 
called  "the  finthcr  of 
the  iron-trade  of  the 
British  nation,"  and  it 
is  estimated  that  his  in- 
vention has,  during  this 
century,  given  employ- 
ment to  six  millions  of 
persons,  and  increased  the  wealth  of  Great  Britain  by 
three  thousand  millions  of  dollars.  In  his  experiments 
for  perfecting  his  process  Mr.  Lort  spent  his  fortune, 
and  though  it  proved  so  valuable,  he  died  poor,  having 
been  involved  by  the  ^^overnment  in  a  lawsuit  concern- 
ing his  patent,  which  beggared  him.     Six  years  before 


PHOiNlXVILLE  BRIDGE-WORKS. 


II 


his  death,  the  government,  as  an  acknowledgment  of 
their  wrong,  granted  him  a  j  early  pension  of  a  thou- 
sand dollars,  and  at  his  death  this  miserly  recompense 
was  rediK  '  to  his  widow,  to  six  hinidred  and  twenty- 
five  dolla'j. 

When  iron  is  simply  melted  and  run  into  any  mould 
i  t  s  texture  i  s 
granular,  and 
it  is  so  brittle 
as  to  be  quite 
unreliable  for 
any  use  requir- 
ing much  tensile 
strength.  The 
process  of  pud- 
dling consisted 
in  stirring  the 
molten  iron  run 
out  in  a  puddle, ' 
and  had  the  ef 
feet  of  so  chang- 
ing its  atomic  arrangement  as  to  render  the  process  of 
rolling  it  more  efficacious.  The  ,-.o';ess  of  boiling  is 
considered  an  improvement  upon  this.  The  boiling- 
furnace  is  an  oven  heated  to  an  intense  heat  by  a  fire 
urged  with  a  blast.  The  cast-iron  sides  are  double,  and 
a  constant  circulation  of  water  is  kept  passing  tlirough 
the  chamber  thus  made,  in  order  to  preserve  the  struc- 
ture from  fusion 
by  the  heat.  The 
inside  is  lined 
with  fire-brick 
covered  with 
metallic  ore  and 
slag  over  the 
bottom  and 
sides,  and  then, 
the  oven  being 
charged  with  the 
pigs  of  iron,  the 
heat  is  let  on. 
The  i)igs  melt, 
and  the  oven  is 
filled  with  molten  iron.  The  puddler  constantly  stirs 
this  mass  with  a  bar  let  through  a  hole  in  the  door,  until 
the  iron  boils  up,  or  "ferments,"  as  it  is  called.  This 
fermentation  is  caused  by  the  combustion  of  a  portion 
of  the  carbon  in  the  iron,  and  as  soon  as  the  excess  of 
this  is  consumed,  the  cinders  and  slag  sink  to  the  bot- 
tom of  the  oven,  leaving  the  semi-fluid  mass  on  the 
top.  Stirring  this  about,  the  puddler  forms  it  into 
balls  of  such  a  size  as  he  can  conveniently  handle, 
which  are  taken  out  and  carried  on  little  cars,  made  to 
receive  them,  to  "the  squeezer." 


CAKKYINi;  THU    IKON    UALLS 


To  carry  on  this  process  properly  requires  great  skill 
and  judgment  in  the  puddler.  The  heat  necessarily 
generated  by  the  operation  is  so  great  that  very  few 
persons  have  thp  physical  endurance  to  stand  it.  So 
great  is  it  that  the  clothes  upon  the  person  frequently 
catch  fire.     Such  a  strain  upon  the  physical  powers 

naturally  leads 
those  subjected 
to  it  to  indulge 
in  excesses.  The 
perspiration 
which  flows  from 
the  puddlers  in 
streams  while 
engaged  in  their 
work  is  caused 
by  the  natural 
effort  of  their 
bodies  to  pre- 
serve themselves 
from  injury  by 
keeping  their  normal  temperature.  Such  a  consump- 
tion of  the  fluids  of  the  body  causes  great  thirst,  and 
the  exhaustion  of  the  labor,  both  bodily  and  mental, 
leads  often  to  the  excessive  use  of  stimulants.  In  fact, 
the  work  is  too  laborious.  Its  conditions  are  such  that 
no  one  should  be  subjected  to  them.  The  necessity, 
however,  for  judgment,  experience,  and  skill  on  the 


BOILlNG-FUKNACr. 


RtlTARV  SgllEEZFH. 


part  of  the  operator  has  up  to  this  time  prevented  the 
introduction  of  machinery  to  take  the  place  of  human 
labor  in  this  process.  The  successful  substitution  in 
modern  times  of  machines,  for  jjerforming  vprin-.^ 
operations  which  formerly  seemed  to  require  the  intel- 
ligence and  dexterity  of  a  living  being  for  their  execu- 
tion, justifies  the  expectation  that  the  study  now  being 
given  to  the  organization  of  industry  will  lead  to  the 
invention  of  machines  whicli  will  obviate  the  necessity 
for  human  suffering  in  the  process  of  puddling.  Such 
a  consummation  would  be  an  advantage  to  all  classes 
concerned.  The  attempts  which  have  been  made  in 
this  direction  have  not  as  yet  proved  entirely  successful. 
In  the  squeezer  the  glowing  ball  of  white-hot  iron  is 
placed,  and  forced  with  a  rotary  motion  through  a 


12 


PHCENIXVILLE   BRIDGE-WORKS. 


spiral  passage,  the  diameter  of  which  is  constancy  di- 
minishing. Tlie  eff'  I  t  of  tliis  operation  is  to  squeeze 
all  the  slag  and  cinder  out  of  the  ball,  and  force  the 
iron  to  assume  the  shape  of  a  short  thick  cylinder  called 
"a  bloom."  This 
process  was  former- 
ly performed  b  y 
striking  the  ball 
of  iron  repeatedly 
with  a  tilt-hammer.' 
The  bloom  isnov 
re-heated  •  and  sub- 
jected to  the  process 
of  rolling.  "The 
rolls"  are  heavy 
cylinders  of  cast- 
iron  placed  almost 
in  contact,  and  re- 
volving rapidly  by 
steam-power.  The 
bloom  is  caught  be- 
tween these  rollers, 
and  passed  back- 
ward and  forward 
until  it  is  pressed 
into  a  flat  bar,  ave- 
raging from  four  to 
six  inches  in  width, 
and  about  an  inch 
and  a  half  thick. 
These  bars  are  then 
cut    into     s  li  o  r  t 

lengths,  piled,  heated  again  in  a  furnace,  and  re-rolled. 
After  going  througli  this  process  they  form  the  bar  iron 
of  commerce.  From  the  iron  "educed  into  this  form 
the  various  parts  used  in  the  construction  of  iron  bridges 
are  made  by  being  rolled  into  shape,  the  rolls  through 

which    the 

■  I'lHiTii;  ■^i'iiiii''.;  various 

parts  pass 
having 
grooves  of 
the  form  it 
is  desired 
to  give  to 
the  pieces. 
T  h  e  s  e 
rolls,  when 
they  arc 
driven  by  steam,  obtain  this  generally  from  a  boiler 
placed  over  the  heating-  or  puddling-furnace,  and 
heated  by  tlie  waste  gases  from  the  fun. ace.  This  ar- 
rangement was  first  made  by  John  Griffie,  the  super- 
intendent   of  the   Phoenix    Iron-Works,  under  whose 


COLI>   SAW 


direction  the  first  rolled  iron  beams  over  nine  inches 
deep  that  were  ever  made  were  produced  at  these  works. 
The  process  cf  rolling  toughens  the  iron,  seeming  to 
draw  out  its  fibres;  and  iron  that  has  been  twice  rolled 

i  s  considered  fi  t 
for  ordinary  uses. 
For  the  various 
parts  of  a  bridge, 
however,  where 
great  toughness  and 
tensile  strength  are 
necessary,  as  well  as 
uniformity  of  tex- 
ture, the  iron  is 
rolled  a  third  time. 
The  bars  are  there- 
fore cut  again  into 
pieces,  piled,  re- 
heated, and  rolled 
again.  A  bar  of 
iron  which  has  been 
rolled  twice  is 
formed  from  a  pile 
of  fourteen  separate 
pieces  of  iron  that 
have  been  rolled 
only  once,  or 
"muck  bar,"  as  it 
is  called  ;  while  the 
thrice-rolled  bar  "s 
made  from  a  pile  of 
eight  separate  pieces 
of  do'ihle-rolled  iron.  If,  therefore,  one  of  the  original 
pieces  of  iron  has  any  flaw  or  defect,  it  will  form  only 
a  hundred  and  twelftii  part  of  the  thrice-rolled  bar.  The 
uniformity  of  texture  and  the  toughness  of  the  bars 
which  have  been  thrice  rolled  are  so  great  that  they 
may  be 
twisted, 
cold,  into  a 
knot  with- 
out showing 
any  signs  of 
fracture. 
The  l)ar»  of 
iron,  wheth- 
er hot  or 
cold,     are 

,  HOT  SAW. 

sawn  to  the 

various  required  lengths  by  the  hot  or  cold  saws  shown 
in  the  illustrations,  which  revolve  with  great  rapidity. 
For  the  columns  intended  to  sustain  the  compressive 
thrust  of  heavy  weights  a  form  is  used  in  this  esiablish- 
ment  of  their  own  design^  and  to  which  the  name  of 


I- ' ' 


i 


PHCENIXVILLE  BRIDGE-WORKS. 


»3 


1^' 

I 


Kivr.riNi;  A  column. 


the  "  PhcEiiix  column"  has  been  given.  They  are 
tubes  made  from  four  or  from  eight  sections  rolled  in 
tlie  usual  way  and  riveted  together  at  their  flanges. 
(See  Plate  XV.)  When  necessary,  such  column:  ;,.v. 
joined  together  by  cast-iron  joint-blocks,  with  circular 
tenons  which  fit  into  the  hollows  of  each  tube. 
To  join  two  bars  to  resist  a  strain  of  tension,  links 

or  e  y  e- 
bars  are 
used  from 
three  t  o 
six  inches 
wide,  and 
as  long  ns 
may  be 
needed. 
At  each 
end  is  an 
enlarge- 
ment with  a  hole  to  receive  a  pin.  In  this  way  any 
number  of  bars  can  be  joined  together,  and  the  result 
of  numerous  experiments  made  at  this  establishment 
has  shown  that  under  sufficient  strain  they  wiil  part  as 
)ften  in  the  body  of  the  bar  as  at  the  joint.  The  heads 
upon  these  bars  are  made  by  a  process  known  as  die- 
forging.  The  bar  is  heated  to  a  white  heat,  and  under 
a  die  worked  by 
hydraulic  pres- 
sure the  head  is 
shaped  and  the 
hole  struck  at 
one  operation. 
Tliis  method  of 
joining  by  pins 
is  much  more 
relial)le  than 
welding.  The 
pins  are  made 
o  f  cold-rolled 
sliafting,  and  fit 
to  a  nicety. 

The  general  view  of  the  machine-shop,  which  covers 
more  than  an  acre  of  ground,  shows  the  various  ma- 
chines and  tools  by  which  iron  is  planed,  turned, 
drilled,  and  handled  as  though  it  were  one  of  the  soft- 
est of  materials.  Such  a  machine-shop  is  one  of  the 
wonders  of  this  century.  Most  of  the  operations  per- 
formed there,  and  all  of  the  tools  with  which  they  are 
done,  are  due  entirely  to  modern  invention,  many  of 
tliem  within  the  last  ten  years.  By  means  of  this  aj)- 
plication  of  machines  great  accuracy  of  work  is  obtained, 
and  each  part  of  an  iron  bridge  can  be  exactly  dupli- 
cated if  necessary.  This  method  of  construction  is 
entirely  American,  the  English  still  Iniilding  their  iron 


FUKNAfE   AND    IIYlJHAl'Llf 


bridges  mostly  with  hand-labor.  In  consequence  also 
of  this  method  of  working,  American  iron  bridges, 
despite  the  higher  price  of  our  iron,  en  successfully 
compete  in  Canada  with  bridges  of  English  or  Belgian 
construction.  The  American  iron  bridges  are  lighter 
than  those  of  other  nations,  but  their  absolute  strength 
is  as  great,  since  the  weight  which  is  saved  is  all  dead 
weight,  and  not  necessary  to  the  solidity  of  the  struc- 
ture. The  same  difference  is  displayed  here  that  is 
seen  in  our  carriages  with  their  slender  wheels,  com- 
pared with  the  lumbering  heavy  wagons  of  European 
construction. 

Before  any  practical  work  upon  the  construction  of  a 
bridge  is  begun,  the  data  and  specifications  are  given, 
and  a  plan  of  the  structure  is  drawn,  whether  it  is  for  a 
railroad  or  for  ordinary  travel,  whether  for  a  double  or 
single  track,  whether  the  train  is  to  pass  on  top  or 
below,  and  so  on.  The  calculations  and  plans  are  then 
made  for  the  use  of  such  dimensions  of  iron  that  the 
strain  upon  any  part  of  the  structure  shall  not  exceed  a 
certain  maximum,  usually  fixed  at  ten  thousand  pounds 
to  the  square  inch.  As  the  weight  of  the  iron  is  known, 
and  its  tensile  strength  is  estimated  at  sixty  thousand 
pounds  per  square  inch,  this  estimate,  which  is  techni- 
cally called  "a  factor  of  safety"  of  six,  is  a  very  safe 
one.     In  other  words,  the  bridge  is  planned  and  so 

constructed  that 
i  n  supporting 
its  own  weight, 
together  with 
any  load  o  f 
locomo  t  i  ves 
or  cars  which 
can  be  placed 
upon  it,  it  shall 
not  be  sub- 
jected to  a 
strain  over 
o  n  e  -  s  i  X  t  h  of 
i  t  s  estimated 
strength. 

After  the  plan  is  made,  working  drawings  are  pre- 
pared and  the  process  of  manufacture  commences. 
The  eye-bars,  when  made,  are  tested  in  a  testing- 
machine  at  double  the  strain  which  by  any  possibility 
they  can  be  put  to  in  the  bridge  itself.  The  elasticity 
of  the  iron  is  such  that,  after  beirg  submitted  to  a  ten- 
sion of  about  thirty  thousand  pounds  to  the  square  inch, 
it  will  return  to  its  original  dimensions;  while  it  is  so 
tougii  that  the  bars,  as  large  as  two  inches  in  diameter, 
can  be  bent  double,  when  cold,  without  showing  any 
sigr.s  of  fracture.  Having  stood  these  tests,  the  parts 
Of  the  bridge  are  considered  fit  to  be  used. 

When   completed,    the   parts  are   put    together  or 


•f 


14 


PH(.ENIXVILLE  BRIDGE-  WORKS. 


"asseniblcil,"  as  the  technical  phrase  is,  in  order  to 
see  that  tiiey  are  right  in  length,  etc.  Then  they  are 
marked  with  letters  or  numbers,  according  to  the  work- 
ing jiian,  and  shipped  to  the  spot  where  the  bridge  is 
to  be  permanently  erected.  Before  the  erection  can 
be  begun,  however,  a  staging  or  scaffolding  of  wood, 
strong  enough  to  support  the  iron  structure  until  it 
is  finished,  has  to  be  raised  on  the  spot.  When  the 
bridge  is  a  large  one,  this  staging  is  of  necessity  an  im- 
portant and  costly  structure.  An  illustration  on  the  next 
page  shows  the  staging  erected  for  the  support  of  the 
New  River  bridge  in  West  Virginia,  on  the  line  of  the 


Chesapeake  and  Ohio  Railway,  near  a  romantic  spot 
known  as  Hawksnest.  About  two  hundred  yards  below 
this  bridge  is  a  waterfall,  and  while  the  staging  was  still 
in  use  for  its  construction,  the  river,  which  is  very 
treacherous,  suddenly  rose  about  twenty  feet  in  a  few 
hours,  and  became  a  roaring  torrent. 

The  method  of  making  all  the  parts  of  a  bridge  to 
fit  exactly,  and  securing  the  ties  by  pins,  is  peculiarly 
American.  Th.e  plan  still  followed  in  Europe  is  that 
of  using  rivets,  which  makes  tiie  erection  of  a  bridge 
take  much  more  time,  and  costs,  consecpiently,  much 
more.     A  riveted  lattice  bridqe,  one  hundred  and  sixty 


VIKW   OF    MACHINK-Sllnl'. 


feet  in  span,  would  require  ten  or  twelve  days  for  its 
erection,  wiiile  one  of  the  Pluenixville  bridges  of  this 
size  has  been  erected  in  ciglit  and  a  half  hours. 

The  view  of  tlie  Albany  bridge  will  show  the  style 
which  is  technicall)- called  a  "tlirougii"  bridge,  having 
the  track  at  the  level  of  the  lower  chords.  'l"iiis  view 
of  the  bridge  is  taken  from  the  west  side  of  tlie  Hud- 
son, near  the  Delavan  House  in  .Mbanv.  The  curved 
portion  crosses  the  Albany  basin,  or  outlet  of  the  Erie 
Canal,  and  consists  of  seven  spans  of  seventy-three  feet 
each,  one  of  sixty-tliree,  and  one  of  one  hundred  and 
ten.  That  part  of  tiie  bridge  which  crosses  the  river 
consists  of  four  spans  of  one  hundred  and  eighty-five 
feet  each,  and  a  draw  two  hundred  and  seventy-four 
feet  wide.  The  iron-work  in  this  liridge  tost  about 
three  hundred  and  twenty  thousand  dollars. 


The  bridge  over  the  Illinois  River  at  La  Salle,  on  the 
Illinois  Central  Railroad,  shows  the  style  of  bridge 
technically  called  a  "deck"  bridge,  in  which  the  train 
is  on  tlie  to]).  This  bridge  consists  of  eighteen  spans 
of  one  hmulred  and  sixty  feet  ea(  h,  and  cost  one  hun- 
dred and  eighty  thousand  dollars.  Tlie  bridge  over 
the  Kennebec  River,  on  the  line  of  the  Maine  Central 
Railroad,  at  .'Vugusta,  Maine,  is  anotlier  instance  of  a 
"through"  bridge.  It  cost  seventy-five  thousand 
dollars,  has  five  spans  of  one  hundred  ami  eiglity-five 
feet  each,  and  was  built  to  rejilace  a  wooden  deck 
bridge  which  was  carried  away  by  a  freshet. 

The  bridge  on  the  Portland  and  Ogdensburg  Rail- 
road which  crosses  the  Saco  River  is  a  very  general 
type  of  a  through  railway  bridge.  It  <  onsists  of  two 
spans  of  one  hundred  and  eighty-five  feet  each,  and 


PHiENlXVILLE   BRIDGE-  WORKS, 


>S 


(  ost  twenty  thousand  dollars.     The  New  River  bridge 
in  West  Vir},nnia  consists  of  two  spans  of  two  hiinda-d 


and  fifty  feet  each,  and  two  others  of  seventy-five  feet 
each.     Its  cost  was  ahout  seventy  thousand  dollars. 


.<)  v^m».^^sm^sm. 


NliW    KIVHR    IIKIDGR   ON   ITS  STAGING. 


riie  Lyman  Viaduct,  on  the  Connecticut  Air-line     dred  and  thirty-five  feet  high  and  eleven  hundred  feet 
Railway,  at  East  Hampton,  Connecticut,  is  one  hun-     long. 


limin.I-.    AT    AI.nAN\. 


These  specimens  will  show  the  general  chanicter  of  [  employed,  hut  its  brittleness  and  unreliability  have  led 
the  iron  bridges  ercted  in  this  country.  When  iron  :  to  its  rejection  for  the  main  portions  of  bridges.  E.\- 
ivas  first  used  in  constructions  of  this  kind,  cast  iron  was     perience  has  also  led  the  best  iron-bridge-builders  of 


i6 


PHCENIXVILLE   BRIDGE-  WORKS. 


America  to  quite  generally  employ  girders  with  parallel 
ton  and  bottom  members,  vertical  posts  (except  at  the 
ends,  where  they  are  made  inclined  toward  the  centre 
of  the  span),  and  tie-rods  inclined  at  nearly  forty-five 


degrees.      This  form  takes  the  least  material  for  the  re- 
quired strength. 

The  safety  of  a  bridge  depends  qnite  as  much  upon 
the  design  and  proportions  of  its  details  and  coiinec  - 


Ill' 


.^*i 


LA   bALLK    IIKIW;!'.. 


tions  as  upon  its  general  shape.  The  strain  which  will 
compress  or  extend  the  ties,  chords,  and  other  parts 
can  be  calculated  with  mathematical  exactness.  But 
the  strains  coming  upon  the  connections  are  very  often 
indeterminate,  and  no  mathematical  formula  has  yet 
been  found  for  them.     They  are  like  the  strains  which 


come  upon  the  wheels,  axles,  and  moving  parts  of 
carriages,  cars  and  machinery.  Yet  experience  and 
judgment  have  led  the  best  builders  to  a  singular  uni- 
formity in  their  treatment  of  these  parts.  Each  bridge 
has  been  an  experiment,  the  lessons  of  which  have 
been  studied  and  turned  to  the  best  effect. 


BKIUGK  AT  AUGUSTA,   MAINI!. 


There  is  no  doubt  that  iron  bridges  can  be  made 
perfectly  safe.  Their  margin  is  greater  than  that  of 
the  boiler,  the  axles,  or  the  rail.  To  make  them  safe, 
European  governments  depend  upon  rigid  rules,  and 
careful  inspection  to  see  that  they  are  carried  out.  In 
this  country  government  inspection  is  not  relied  on 
with  such  certainty,  and  the  spirit  of  our  institutions 


leads  us  to  depend  more  upon  the  action  of  self-interest 
and  the  inherent  trustworthiness  of  mankind  when  in- 
dulged with  freedom  of  action.  Though  at  times  this 
confidence  may  seem  vain,  and  "rings"  in  industrial 
pursuits,  as  in  politics,  appear  to  corrupt  the  honesty 
which  forms  the  very  foundation  of  freedom,  yet  their 
influence  is  but  temporary,  and  as  soon  as  the  best 


PHCENIXVILLE  JiRIDGE-  WOUk'S. 


»7 


public  sentiment  becomes  convinced  of  the  need  for 
their  removal  their  influence  is  destroyed.  Such  evils 
are  necessary  incidents  of  our  transitional  movement 


toward  an  industrial,  social,  and  political  organization 
in  which  the  best  intelligence  and  the  most  trjstworthy 
honesty  shall  control  these  interests  for  the  best  advan- 


tage of  society  at  large,     in  liic  meanliinc,   tiie  best  ^  taiiily  do  not  desire  to  waste  their  i.ioney  or  to  render 

security 

the  self-i 


for  the  safety  of  iron  bridges  is  to  be  found  in 
-interest  of  the  railway  corporations,  who  cer- 


themselves  liable  to  damages  from  the  breaking  of  their 
bridges,  and  who  consequently  will  employ  for  such 


I'HtlCNIX    WiiUKS 


constructions  those  whose  reputation  has  been  fairly 
earned,  and  whose  character  is  such  that  reliance  can 
be  placed  in  the  honesty  of  their  work.  Experience 
has  given  the  world  the  knowledge  needed  to  build 

3 


bridges  of  iron  which  shall  in  all  possible  contingencies 
be  safe,  and  there  is  no  excuse  for  a  penny-wise-and- 
pound-foolish  policy  when  it  leads  to  disaster. 

Edward  Howland. 


APPENDIX    No.   2. 

LOADS  AND  STRAINS  OF  BRIDGES. 

A  paper  presented  by  JOHN  GRIFFEN  and  THOS.  0.  OLABKE,  OivU  Engineen,  memben  of  the  American  Society 
of  Oivil  Engineers,  at  tlie  Fourth  Annual  Oonrention  of  the  Society,  held  at  Ohioago,  June  6  and  6,  1872. 


How  to  obtain  uniformity  of  strength  is  the  problem 
to  be  solved  by  the  design  of  iron  railway  bridges. 
The  strength  of  the  weakest  bridge,  and  of  tlie  weakest 
part  of  that  bridge,  measures  the  strength  of  all  the 
bridges  on  a  line  of  railway.  The  breaking  of  a  single 
floor  beam  may  wreck  a  train,  and  kill  and  wound 
many  persons;  and  it  is  no  consolation  to  know  that 
all  the  other  floor  beams,  tie  rods,  etc.,  of  other  bridges 
of  the  same  line,  have  a  superabundance  of  strength. 

The  stn^nglh  of  a  bridge  results  from  the  following 
conditions: — 

The  heaviest  loads  to  which  it  can  be  subjected. 

The  maximum  strains  resulting  from  those  loads. 

The  sizes  of  the  tensile  and  compressive  members, 
and  hence  their  strains  per  square  inch  of  area. 

The  available  strength  of  those  members  depending 
upon — First.  The  quality  of  the  iron  of  which  they  are 
made.  Second.  The  cross-section  of  the  struts.  Third. 
The  mode  of  forming  the  connections. 

Errors  of  design  have  been  made  in  respect  to  all 
these  points. 

First.  A  uniform  load  per  lineal  foot  has  been  as- 
sumed for  all  spans,  short  and  long  alike,  while  the 
actual  load  is  greater  for  short,  and  less  for  long,  spans, 
and  is  always  in  excess  of  the  general  load  upon  certain 
parts,  such  as  floor  beams. 

Second.  No  distinction  has  been  made  between  the 
effects  of  the  dead  load  of  the  structure  and  the  moving 
or  live  loac  f  trains,  suddenly  applied  and  accom- 
panied by  s   ^cks  and  vibrations. 

Third.  The  margin  of  safety  between  the  allowed 
strain  and  the  disabling  limit  of  the  iron  has  been  over- 
estimated, as  the  margin  of  safety  of  the  weakest  part 
measures  that  of  the  whole. 

Fourtli.  Sufficient  distinction  has  not  been  made  in 
specifications  between  a  tough  and  elastic  iron,  and 
a  hard  and  brittle  quality,  if  the  ultimate  breaking 
strength  of  both  were  alike. 

Fifth.  The  strains  allowed  upon  compressive  mem- 
bers are  not  based  upon  any  definite  knowledge  of  their 
ultimate  powers  of  resistance. 

These  points  will  be  considered  in  turn,  and  sugges- 
tions will  be  made  toward  a  practice  which  shall  result 
in  uniformity  of  strength  in  all  lengths  of  span,  in  all 
(18) 


parts  of  every  span,  so  that  one  part  shall  not  give  way 
before  another. 

The  standard  of  strength  must  finally  be  determined 
by  the  engineer  for  each  particular  case.  It  would  be 
useless  to  lay  down  any  rules  upon  this  point.  F<arh 
man  must  be  free  to  settle  it  for  himself  But  when  he 
has  decided  it,  and  says,  "I  will  adopt  a  margin  of 
safety  of  three,  four,  five,  or  six,"  as  the  case  may  be, 
he  wishes  to  feel  certain  that  all  his  spans,  and  all  their 
parts, 'form  no  exception  to  this  rule.  Uniformity  of 
strength  will  then  be  attained;  how  much  strength  to 
give  will  be  always  an  open  question. 

I.  What  are  the  actual  loadsto  which  railway  bridges 
are  subjected  ? 

In  Table  No.  i,  accompanying  this  paper,  will  be 
found  a  list  of  the  weights  and  dimensions  of  the  prin- 
cipal types  of  locomotives  now  used  upon  American 
railways,  divided  into  three  classes. 

The  first  includes  those  engines  of  exceptional  di- 
mensions and  weights  which  are  used  for  pushing  trains 
up  heavy  grades.     Fortunately,  their  speed  is  slow. 

The  second  class  includes  heavy  freight  and  coal 
engines,  whose  average  speed  is  ten  to  twelve  miles  an 
hour. 

The  third  class  the  common  form  of  four-driver  i)as- 
senger  engines,  which  cross  bridges  at  from  twenty  to 
fifty  miles  an  hour. 

Class  four  contains  the  various  kinds  of  cars, — pas- 
senger, freight,  and  coal. 

The  following  points  may  be  discovered  from  inspec- 
tion of  this  table : 

That  the  weights  of  engines  and  loaded  tenders  aver- 
age from  2300  to  2700  pounds  per  foot  of  track  occu- 
pied, and  that  the  weights  of  tenders,  separately,  are 
but  little  less. 

That,  owing  to  the  concentrated  weight  of  engine 

over  drivers,  the  loads  carried  by  spans  of  less  than  100 

feet  will  exceed  these  weights.     As  there  are  so  many 

different  types  of  engines  we  must  select  one  of  average 

!  dimensions  and  weight,  leaving  provision  to  be  made 

!  for  the  passage  of  exceptionally  heavy  engines  in  the 

I  margin  of  safety  which  is  to  be  fixed  by  the  engineer 

i  of  the  bridge. 

Take,  therefore,  an  engine  whose  total  weight  with 


PH(ENIXVJLLE  BRIDGE-WORKS. 


«9 


loaded  tender  is  135,000  puunds,  occupying  with  pilot 

fifty  feet  of  track,      ''  °°  =  3500  pounds  per  foot: 

distance  occupied  by  wheel  base  of  engine  and  tender 

alone  is  41 1^  feet,  =1000  pounds  per  foot; 

41.5 

distance  occupied  on  track  by  the  concentrated  weight 

over  drivers,  say  17  feet,  and  weight  60,000  pounds, 

60,000 

-  :^  3530  pounds  per  foot;   if  the  driving-wheel 

,                 60,000  ,  ,         .,  ,      ,  . 

base  is  15, =  4000  pounds  per  foot ;  if  the  driv- 
ing-wheel base  is  13  feet,  — ' —  =;  5000  pounds  per 

13 

foot.     This  will  give  us  the  following  loads : 


Spans  13  feet  ami  under    . 

.    5000  pounils 

per  foot. 

"     la  to  17  feet 

4000 

" 

"      " 

"     17  "  3.5    "... 

.    3S0O 

" 

"      " 

"     as  "  83    "          .        . 

3000 

" 

"      " 

"    83  "  no" 

.    3500 

" 

"      " 

Floor  beams  under  12  feet  apart,  and  track  stringers 
less  than  13  feet  long,  will  carry  5000  pounds  per  foot. 

Floor  beams  12  to  15  feet  apart,  and  track  stringers 
12  to  15  feet  long,  will  carry  4000  pounds  per  foot. 

Inasmuch  as  the  weight  per  foot  of  cars  is  consider- 
ably less  than  that  of  engines,  in  spans  of  over  100  feet, 
the  actual  load  per  foot  will  diminish  with  the  length 
of  span. 

These  results  have  been  arranged  in  Table  No.  2, 
showing,  for  different  spans,  the  weights  caused  by — 

I.  All  locomotives. 

3.  Reading  coal  cars,  drawn  by  two  Reading  standard 
coal  engines. 

3.  Same  cars  by  one  siniilar  engine. 

4.  Pennsylvania  box  freight  cars,  drawn  by  two  stan- 
dard freight  engines. 

5.  Same  cars  by  01     similar  engine. 

6.  Pullman  palace  cars,  drawn  by  one  New  York 
Central  passenger  engine. 

These  are  the  ma.ximum  loads  which  can  come  upon 
the  chord  systems  of  any  of  the  forms  of  girder  truss, 
upon  the  primary  system  of  a  Fink  truss,  or  upon  the 
arch  and  chord  of  a  bowstring.  Owing  to  the  excess 
of  weight  of  the  locomotive  above  that  of  cars,  the  loads 
upon  the  panel  systems  of  girder,  trusses,  and  bow- 
strings, and  the  subsidiary  systems  of  the  Fink  truss 
will  be  in  excess,  and  should  be  taken  for  all  spans  at 
not  less  than  3500  pounds  per  foot. 

II.  It  has  been  stated  that  it  is  not  customary  to  make 
any  distinction  between  the  effects  of  the  dead  load  of 
the  bridge  and  the  live  load  of  trains.  This  varies 
very  much  in  ratio,  according  to  the  length  of  span. 
Table  No.  3  shows  what  the  ratio  of  dead  to  live 
loads  is  for  different  spans. 


There  ran  be  no  doubt  but  that  the  short  spans,  where 
nine-tenths  is  live  load,  accompanied  by  vibr.-ition,  are 
more  severely  strained  than  the  long  bridges  where  half 
the  load  is  tpiiescent.  It  would  appear  that  I'le  margin 
of  safety  ought  to  be  greater  upon  short  than  upon  long 
spans,  in  order  to  give  uniform  strength. 

It  is  difficult  to  say  what  the  exact  diffenrnce  is  be- 
tween the  effects  of  dead  and  live  loads.  Professor 
Macqiiorn  Rankine,  a  very  high  authority,  states  in  his 
"Applied  Mechanics,"  "a  suddenly  applied  force  is  I 
equivalent  in  strain  to  twice  the  same  force  gradually 
applied." 

This  conclusion  is  confirmed  both  by  the  experiments 
made  by  order  of  the  English  Commissioners  upon  the 
application  of  iron  to  railway  structures  so  far  back  as 
1849,  iiid  l^y  'he  later  experiments  of  Fairbairn,  which 
will  not  be  quoted  here  in  detail,  as  they  are  to  be  found 
in  all  the  books. 

From  them  it  appeared  that  a  tensile  strain  of  six 
tons  per  sauare  inch,  applied  to  the  bottom  flange  of  a 
riveted  plate  girder,  and  accompanied  by  vibrations 
made  to  resemble,  as  much  as  possible,  those  caused 
by  a  passing  train,  did  not  break  the  girder,  although 
repeated  over  three  millions  of  times.  But  when  the 
strain  was  increased  to  eight  tons  per  square  inch,  it 
broke  after  300,000  further  applications.  As  the  break- 
ing strength  of  average  English  plate  ranges  from  twenty 
to  twenty-two  tons,  it  would  appear  .'hat  the  effect  of 
live  load  was  more  than  twice  as  severe  as  dead  load. 
It  is  to  be  regretted  that  Dr.  Fairbairn  did  not  have 
the  girders  made  of  exactly  the  same  dimensions,  and 
of  the  same  iron  ;  ascertain  the  breaking  static  weight 
of  one,  and  then  apply  one-half  of  this  as  live  weight, 
and  see  how  many  applications  it  would  bear  before 
breaking. 

If  we  agree  with  Rankine  and  Fairbairn,  that  the 
destructive  effect  of  a  live  load  is  double  that  of  a  dead 
load,  our  course  is  clear.  A  suggestion,  originally 
made  it  is  believed  by  Unwin,  in  his  treatise  upon  iron 
bridges,  points  the  way  to  a  simple  solution  of  the 
problem.  Multiply  the  live  load  by  two,  and  add  it  to 
the  dead  load.  Their  sum  will  be  a  load  which  may 
safely  be  treated  as  an  all  dead  load,  and  a  strain  per 
square  inch  and  margin  of  safety  used  such  as  is  proper 
for  dead  loads. 

Table  No.  4  shows  the  equivalent  dead  loads  ap- 
plicable to  all  spans.  If  these  loads,  or  rather  this 
principle  of  fixing  loads,  be  adopted  by  engineers,  one 
uncertain  element  will  be  eliminated  from  the  problem, 
and  the  only  point  left  open  will  be  what  limit  of  strain 
to  put  upon  the  iron. 

III.  It  has  been  stated  that  the  value  of  the  factor  or 
margin  of  safety  is  commonly  over-estimated.  It  is  not 
uncommon  to  read  in  specifications  that  the  factor  of 


J 


20 


PHCENIXVILLE  BRIDGE-  WORKS. 


\i\ 


■|^ 


■?;i 


safety  shall  be  six,  meaning  that  the  working  strain  shall 
be  one-sixth  of  the  ultimate  breaking  strain. 

A  little  consideration  will  show  that  the  true  margin 
of  safety  is  the  difference  between  the  working  strain 
and  that  strain  which  would  give  the  iron  a  permanent  i 
set  and  unfit  it  for  use,  either  by  crippling  *he  com-  | 
pressive  members  or  by  stretcliing  the  tension  members 
so  that  the  bridge  would  become  distorted  and  "sag" 
below  a  level  line.     Even  before  this  point  was  reached,  I 
the  iron  in  tension  would  have  become  "overstrn'  led,"  j 
causing  its  particles  to  sufter  permanent  derai  ^jnient.  j 
Although  this  "set,"  as  il  's  called,  does  not  diminish  j 
the  ultimate  capacity  of  the  iron  to  support  a  dead 
load,  yet,  as  has  been  pointed  out  by  Stoney,  when  the 
"stretch"  is  taken  out  of  an  originally  tough  piece  of 
iron,  it  becomes  brittle.     It  is  well  known  that  a  chain  j 
that  has  been  overstrained  in  testing  is  liable  to  snap  i 
off  with  less  than  its  proof  load.  j 

This  limit  of  elasticity  of  wrought  iron  under  tension  ' 
is  that  point  at  which  the  elongations  cease  to  be  in 
uniform  proportion  to  equal  additions  of  load,  and 
coincides  very  nearly  with  the  point  at  which  visible 
set  takes  j)lace.     It  does  not  vary  much  from  one-half 
of  the  ultimate  sti'ength  of  the  iron.     Common  English 
plate,  bar,  and  angle  iron,  of  an  ultimate  strengtli  of  ; 
from  twenty  to  twenty-two  tons  per  square  inch,  has  | 
an  elastic  limit  of  not  over  ten  tons  per  square  inch. 
The  highest  grades  of  English  and  American  double  ; 
refined  bar  iron  of  an  ultimate  strength  of  55,000  to 
60,000  pounds  per  square  incii,  have  an  elastic  limit  of 
from  25,000  to  30,000  pounds  per  square  inch  ;  hence  a  | 
working  strain  of  io,ooo  i^ounds  per  square  inch  gives  i 
an  available  margin  of  strength  or  safety,  or  whatever 
term  ve  may  prefer  to  call  it,  of  from  two  to  three,  j 
instead  of  six.  ! 

Whatever  the  engineer  selects,  it  shoukl  be  enough 
to  allow  for — i.  I'ossible  inequality  of  material.  2. 
Imperfection  of  workmanship.  And  3.  The  effects  of 
deterioration,  arising  boih  from  use  and  from  natural 
causes. 

A  dread  of  inequality  of  material  is  the  reason  why 
engineers  prefer  wrought  iron  to  ( ast  iron  or  to  steel 
for  the  construction  of  bridges.  If  the  enginei'r  could 
always  depend  upon  getting  such  a  tpiality  of  cast  iron 
as  the  late  General  Rodman  made  for  artilier}-,  which, 
was  worked  up  to  a  tensible  strain  of  27,000  pounds 
per  square  inch,  and  was  1  ally  more  like  cast  steel  than 
iron,  his  objections  to  the  use  of  cast  iron  would  vanish. 

It  has  been  stated  that  in  experiments  '.poii  the 
material  for  the  St.  Louis  bridge,  some  steel  belts, 
5^  inch  diameter,  broke  with  30,000  pounds  per 
square  inch,  and  no  elongation ;  while  small  bolts  i/^^ 
inch  diameter,  of  the  same  material,  bore  100,000 
pounds  per  square  inch,  and  elongated  consideralilv. 


Imperfection  of  workmanship  should  not  be  found  in 
our  American  bridges  which  are  made  by  machine  tools. 
In  riveted  lattice  and  plate  girders  it  is  a  serious  cause' 
of  the  actual  strength  falling  below  that  given  by  cal- 
culations. Giving  a  margm  of  strength  beyond  what 
seems  to  be  required,  is,  as  we  have  stated,  a  recogni- 
tion of  the  fact  that  iron  bridges  will  decay  like  all  J 
human  works.  ' 

But  it  is  not  so  generally  known  that  if  a  bridge  has 
not  enough  iron  in  certain  parts,  although  built  of  good 
iron  and  put  together  strongly,  it  will  wear  out  under 
a  heavy  traffic,  just  as  locomotives,  cars,  and  rails  wear 
out.  One  or  two  instances  will  illustrate  this.  Where 
pin  connections  are  used,  owing  to  the  concentration 
of  strains  which  comes  upon  a  pin,  it  is  necessary  to 
"reinforce,"  as  it  is  termed,  the  plates  of  iron  upon 
which  the  ])ins  bear,  and  thus  increase  the  bearing  sur- 
face until  the  pressure  is  reduced  to  7000  01  8000  pounds 
per  square  inch,  or  else  the  pin  will  cut  into  the  iron, 
or  the  iron  into  the  pin. 

In  the  Crumlin  viaduct,  as  originally  built  with  pin 
connections,  this  principle  was  not  recognized,  enough 
beaming  surface  was  not  given,  and  the  pin-holes  became 
enlarged.  The  pins  were  removed,  and  the  struts 
riveted  to  the  chords,  and  this  example  is  frequently 
quoted  to  show  the  superiority  of  riveted  over  pin 
connections,  while  in  reality  it  only  shows  imperfect 
design. 

Another  still  more  striking  example  can  be  found 
nearer  home.  On  the  Reading  railway,  plate  girder 
bridges  of  25  feet  span  and  under  were  originally  pro- 
portioned for  a  rolling  load  of  two  tons  per  foot  of 
track.  It  was  found  that  under  the  heavy  traffic  of  that 
road,  the  webs  of  these  girders  at  the  delivery  end 
crushed  or  buckled.  They  have  since  been  rebuilt,  or 
strengthened  and  proportioned  for  a  rolling  load  of  four 
tons  per  foot  of  track,  and  now  wear  very  well. 

IV.  Whatever  be  the  adopted  ?nargin  of  safety,  it 
would  appear  that  a  larger  margin  should  be  allowed  in 
the  case  of  hard  and  brittle  iron  than  in  that  of  a  tough 
and  ductile  quality.  But  tliis  is  just  what  most  bridge 
specifications  do  not  do. 

The  experiments  of  Kirkaldy  have  clearly  shown  that 
a  high  ultimate  breaking  strength  may  be  due  to  the 
iron  being  tough,  or  r.-.erely  to  its  being  hard  and  un- 
yielding. In  the  former  case,  it  will  "draw  down" 
and  stretch  considerably  before  breaking;  in  the  latter, 
it  will  snap  short  off  with  but  little  elongation  and  con- 
traction of  area  at  the  point  of  fracture.  One  is  tough, 
the  other  is  brittle,  and  yet  both  may  have  an  equally 
great  ultimate  strength.  How  shall  we  know  them 
apart  ? 

The  required  iron  should  not  be  too  soft,  the  limit 
of  elasticity  should  not  fall  below  25,000  pounds  per 


PHCENIXVILLE  BRIDGE-WORKS. 


21 


square  Inch  before  showing  visible  set.  The  breaking 
strength  should  run  from  55,000  to  60,000  pounds  per 
square  inch.  A  bar  a  foot  long,  and  of  one  squar'- 
inch  area,  should  elongate  at  least  15  per  cent,  before 
breaking. 

As  it  is  not  always  easy  to  measure  accu-ately  the 
contracted  area  at  the  point  of  rupture,  there  is  no 
simpler  nor  better  mode  of  testing  ductility  than  by 
bending  the  bar  cold,  and  such  a  bar  should  bend 
double,  cold,  without  any  signs  of  fracture. 

Mr.  G.  Berkeley,  in  his  valuable  paper  read  before 
the  London  Institution  of  Civil  Engineers  at  the  session 
of  1870,  states  his  experience  with  English  irons  as 
follows: — "Experience  extending  over  twenty  years, 
and  comprising  many  thousands  of  experiments,  has 
proved  that  a  quality  of  iron  can  be  obtained  at  the 
current  prices  of  the  day,  which  will  bear  the  following 
tests: — 

"  For  plates,  an  average  breaking  strength  of  20  tons 
per  square  inch,  and  a  minimum  of  19  tons  per  square 
inch,  and  an  average  stretch  of  1  inch  in  twelve  lineal 
=  8.33  per  cent. 

"  For  angle  and  T  irons,  an  average  breaking  strength 
of  22  tons  per  square  inch,  and  an  average  stretch  of 
i^  inches  in  twelve  lineal^  10.5  per  cent. 

"  For  rivet  iron,  an  average  breaking  strength  of  18 
tons  per  circular  inch." 

Common  American  bar  iron  will  not  ordinarily  bear 
over  50,000  pounds  ultimate  strength,  will  not  elongate 
over  8^  percent.,  and  will  show  signs  of  fracture  when 
bent  cold  over  45  degrees. 

The  undersigned  have  tested  iron  as  brittle  as  this, 
and  quite  unfit  to  go  into  a  bridge,  the  breaking 
strength  of  which  was  over  60,000  pounds  per  square 
inch. 

Engineers  should  provide  such  tests  in  their  specifi- 
cations as  will  distmguish  the  two  sorts  apart,  and  if 
they  admit  the  use  of  the  lower  grade  iron,  should  dis- 
cri:ninate  by  fixing  a  larger  margin  of  safety  than  for 
the  tougher  and  better  iron.  If  they  do  not,  they  will 
be  pretty  sure  to  get  the  poorer  quality,  as  it  costs  less 
money,  and  the  reason  wiiy  will  be  sliown. 

Tlie  mode  of  making  refined  iron  at  Piicenixville  is 
to  take  a  high  quality  of  gray  forge  pig  iron,  and  work 
it  in  a  furnace  by  the  process  technically  known  as 
"boiling,"  the  boiling  furnace  being  "  fettled"  with 
ore.  This  pig  iron  when  "  brought  to  nature"  is 
balled  up  in  the  furnace  in  the  usual  way,  squeezed  in 
a  Burden  squeezer,  and  then  rolled  into  a  flat  bar, 
technically  known  as  a  "muck  bar,"  or  No.  i  bar. 

From  each  heat  so  made  one  bar  is  taken  and  btnt 


to  an  angle  of  45  degrees  cold ;  if  it  stands  without 
any  signs  of  fracture  the  heat  is  passed  as  good,  if  not, 
it  is  rejected. 

The  iron  that  has  passed  this  test  is  piled,  charged 
in  a  heating  furnace,  heated  and  rolled  into  flat  bars. 
This  is  called  No.  2  bar,  and  is  sold  as  "Phoenix 
Best."  The  iron  so  rolled  is  again  cut,  piled,  and 
rolled  into  the  finished  bar,  and  is  called  No.  3  bar, 
and  is  the  iron  sold  by  the  Phoenix  Iron  Co.  as  "  Phoenix 
Best  Best."  A  bar  of  this  iron,  25^  inches  diameter, 
has  been  tent  cold  so  that  the  sides  came  in  close  con- 
tact without  showing  the  least  signs  of  fracture. 

It  should  be  borne  in  mind  that  the  object  of  re- 
working iron  is  to  refine  it  by  getting  rid  of  the  surplus 
cinder  and  scoria,  making  the  iron  firm  '  .  texture  and 
of  a  more  uniform  quality.  This  uniformity  of  quality 
results  from  the  fact  that  the  pile  from  which  a  bar  of 
No.  2  is  made  consists  of  fourteen  No.  i  bars,  and  the 
pile  of  No.  3  of  eight  No.  2,  so  that  if  by  chance  an 
inferior  muck  bar  had  been  used,  it  would  form  but 
jfr  part  of  the  No.  3,  or  "  Best  Best"  bar. 

All  iron  improves  up  to  the  third  working,  but  if  the 
quality  of  the  pig  is  not  suitable  no  amount  of  working 
will  make  the  product  good  iron;  hence  the  necessity 
for  tests  as  to  toughness  and  stretching. 

The  ordinary  iron  of  commerce  is  made,  as  a  rule, 
from  an  inferior  quality  of  pig,  is  frequently  worked  in 
its  conversion  from  carbonate  to  metallic  iron  by  the 
process  practically  known  as  puddling,  instead  of  boil- 
ing, and  is  only  once  worked  from  the  puddle  or  muck 
bar,  corresponding  to  No.  2  iron. 

It  is  also  made  sometimes  from  scrap  iron  and  often 
from  old  rails.  Neither  of  these  modes  gives  reliable 
iron,  as  there  is  no  certainty  of  the  quality  of  the  scrap 
used,  though  bar  iron  made  from  scrap  is  ordinarily 
reckoned  as  good  quality.  Iron  from  old  rails  is 
always  inferior,  and  not  to  be  trusted  for  the  uses  of  a 
high-grade  iron,  as  rails  are  generally  made  in  the  first 
place  of  inferior  iron. 

Hence  it  follows  that  a  reliable  iron  for  bridge  pur- 
poses should  be  made  of  a  known  quality  of  pig,  worked 
in  the  best  way  in  the  boiling  furnace,  tested  in  the 
muck  bar,  and  cut,  piled,  heated,  and  rolled  once  or 
twice  thereafter,  according  as  single-  or  doubie-refined 
iron  is  needed. 

It  is  not  to  be  expected,  nor  is  it  desirable,  that  the 
engineer  should  dictate  the  process  of  manufacture,  but 
lie  should  establish  such  tests  in  his  specification  as 
will  distinguish  an  inferior  from  a  high  quality  of  iron, 
and  what  these  tests  should  be  has  been  previously 
stated. 


22 


PHCENIXVILLE  BRIDGE  WORKS. 


elf 


Table   No.  i. 

ACTUAL  WEIGHTS  OF  ENGINES,   TENDERS,   CARS,    ETC. 


No. 


DESCRIPTION. 


No.  of  No.  of 
Driving  ,  Truck 
Wheels.  I  Wheels. 


Concentrated 

weight  on 

Drivers  divided 

hy  length  of 

driving-wheel    iperfut)t. 

base. 


Result- 
ing 
weight 


Result- 


Total  weight 

of  engine  and 

loaded  lender 
<livided  by  dis-  M^ 

lance  covered  on         P   . 

track,  includ-     P"-' '""'• 
ing  pilot.        I 


CLASS    No.    1.— "PUSHERS." 


Reading  Railway  Tank,  all 

Reading  Railway  Tank,  with  tender 

Pennsylvania  Railway,  with  tender 

Hallimorc  &  Ohio  Railw.-\y,  with  tender.. 
Fairlie  double-endcr 


\2 

None. 

lO 

•• 

8 

8 

a 

13 

None. 

103,000  I 


19  ft.  7  in. 
82,21x1 

15  ft.  8  in. 
80,000 

22  ft. 

84,(X)o 

12  ft.  6  in. 
60,480 

8ft! 


5204 
I     3*^36 

!    6720 
i   7560 


ioa,co3  I 


36  ft. 

132,200 

54  ft.  I  in. 
140,000 

54  ft. 

128,000 
120,900 


2833 
2448 
2595 
2415 
2326 


CLASS    No.    2.-HEAVY    COAL    AND     FREIGHT. 


Chicago,  Burlington  &  Quincy,  Freight 

Reading,  standard  coal 

Pennsylvania,  standard  freight 

Delaware,  Lackawanna  &  Wilmington,  standard  freight.. 
New  York  Central,  special  freight 


Erie  broad  gauge,  special  freight.. 


12  ft. 

53,000 

9  ft.  6  in. 

54,500 

12  ft.  5  in. 
71,5m 

12  ft. 
65,oo<j 

15  ft.  6  in. 
7^,156 

14  ft.  6  in. 


6000 

5578     I] 
4360     . 


5948 


4'93 


4976 


l| 


13  8, (XXI 

53  ft.  6  in. 
122,128 

50  ft.  3  in. 
129,900 

54  ft. 
1 38,900 

54  ft- 
iao,tx» 

45  ft. 
■37,444 

54  ft. 


2392 
2430 
2405 
2572 
2666 

2545 


CLASS    No.    3.— MIXED     PASSENGER    AND     FREIGHT    AND     PASSENGER. 


4 
4 
4 
4 
4 



4 
4 
4 

4 
4 

8 

41,440 

6376 

3887 

1 

5675     1 

5376 

546, 

)606  to 
5550 

•  ■5,<84 

45  ft.  7  in- 
103,260 

2526 
2325 
2342 
2275 
2272 

1650  to 

'25>» 

12 

6  ft.  6  in. 
25,264 

6  ft.  6  in. 
45,400 

■3 

43  ft.  10  in. 
125,300 

8  ft. 
40,320 

53  ft.  6  in. 
1 1 2 ,000 

16 
>7 

New  York  Central,  standard  pa-ssenger  and  freight 

7  ft.  6  in. 
40,000 

49  ft. 

lOO.fKX* 

7  ft.  6  in. 
16,50*1  ti» 

25,0  X) 

44  ft. 

33,otKi  to 
50,t)tw 

20  ft. 

4  ft.  6  in. 

CLASS     No.    4.— LOADED    CARS. 


Pennsylvania  Railway,  sleeping  and  passenger  ca 

Pennsylvania  Railway,  box  freight  cars 

Reading,  long  coal  cars 

Lehigh  Valley,  short  coal  cars 

Pullman  palace  and  steeping  cars 


57,000 
64  ft.  2  in. 

42,0(X> 

3>ft. 

40,0110 

22  ft. 

19, OCX) 

■3  ft. 

7  I  /k*! 

75  ft. 


890 

■355 
1818 
1461 
954 


PHCENIXVILLE  BRIDGE-WORKS. 


23 


Table  No.  2. 

WEIGHT  IN  POUNDS  PER   FOOT  RUN  OF  TRACK,  FOR  DIFFERENT  SPANS  AND  KINDS  OF 

TRAINS. 


Length  of  Spans  in  Feet. 


UiuIlt  13.. 
12  to  17.. 
17  to  25.. 
25  to  8^.. 
8j   In  iKi.. 

tlo.. 

125.. 

150.. 

175.. 

2(X).. 
225.. 
250.. 

3<x).. 
35"" 

4rju.. 


I  All 

Lncomotivi 
Engines, 


5cx» 
4000 

350" 
3000 

2500 


COAL 
TRAIN. 
Cars  (No.  ao) 
drawn  by  2  En- 
gines (No.  7). 


2430 
2363 
2275 
2200 
2130 
2100 
2ij68 
2026 

20U0 
2000 


COAL 
TRAIN. 

Cr  i  (No.  20) 

dra.  n  by  I  E 

gine  (No,  7), 


4. 

FREIGHT 
TRAIN. 

Cars  (No.  19) 
I  En-  drawn  by  2  En- 
gines (No.  8), 


2094 

2,.67 

2026 
■JOOO 

>974 
1950 

»943 
1 92 'J 

1907 


FREIGHT 
TRAIN. 

Cars  (No.  \q\ 
drawn  by  I  En- 
gine (No,  8), 


2405 
2262 
2111 

2^,65 

■.Q22 

1S64 

i8u9 

>733 
1679 
1638 


1870 
1809 
1740 
1710 
1665 
1631 
1603 
1363 
1533 
1510 


a. 

PASSENGER 
TRAIN. 

Cars  (No.  22) 
drawn  by  i  En- 
gine (No,  16). 


1481 
1418 
13.1 
■  285 
1344 

I31I 
1186 
II47 

iiao 
I  too 


Table  No.  3. 

RATES  OF  DEAD  TO  LIVE  LOAD,  FOR  DIFFERENT  SPANS. 


LENr.Tii  OP  Spans  in  Fukt. 


Under  12 
12  to  17. 
17  to  25, 
25  to  50. 
50  to   83. 

100. 

llu. 

125. 
150, 

■75. 
2on. 
225, 
250, 
300, 

350 
400. 


DEAD  LOAD 

LIVE  LOAD 

ofHridge.Traci*, 
Rails,  etc., 

of  Coal  Train 

TOTALLOAD, 

■   itll  2  Engines, 

lbs 

,  per  foot. 

per  foot. 

per  foot. 

500 

5000 

5500 

55" 

4000 

4550 

635 

3500 

4125 

700 

3000 

3700 

800 

3CKXJ 

3800 

900 

2500 

3400 

loco 

243" 

3430 

■■35 

2365 

3500 

1.^25 

2275 

3500 

1  }t)0 

2200 

35"" 

15U0 

2130 

363" 

1700 

210" 

381XJ 

2000 

2068 

4068 

1:400 

2026 

4426 

3000 

20UU 

5000 

400U 

2000 

6000 

RATIO  OF  DEAD  TO  LIVE. 


"9 

9' 

12 

88 

■  5 

85 

■9 

81 

21 

79 

26 

74 

3" 

70 

33 

68 

35 

65 

37 

63 

4^ 

59 

45 

55 

49 

51 

54 

46 

60 

40 

66 

34 

Table    No.  4. 

DEAD  AND  LIVE  LOAD  PER  FOOT,  REDUCED  TO  EQUIVALENT  DEAD  LOAD. 


LiiNiiTH  OF  Spans  in  FiiUT. 


Under  12 
12  to  17, 
17  to  25. 
25  tu  50. 
50  10    83. 

110. 
125. 
IS". 
■75. 
200. 
223. 
a, so. 
30-3. 
35"- 
4"". 


<2 

3. 

4. 

De.adI.OADof 

Twice  Live  LOAD 

Sinn  of  cnlumns 

Ilridge,  tic,  per  ft. 

of  Coal  Trail; 

2  and  3,  1. 'Mng 

per  ft. 

Lqnivalem  Dead 
Lo.id  per  ft. 

S(X> 

10,000 

10,500 

55" 

8000 

8550 

(12  s 

7cx)o 

7625 

700 

6vxJO 

6700 

Sou 

6000 

66uo 

yoo 

5«)0 

'^ 

nxjo 

48f)o 

"35 

473" 

5865 

I2J5 

4  5. SO 

5775 

1   ICKJ 

44110 

57>M 

I  SOU 

42(10 

5760 

I7ix> 

4200 

5900 

2000 

4136 

6136 

2400 

4053 

6453 

3000 

4000 

7000 

40U0 

4000 

8<x»i 

APPENDIX    No.   3. 


FROM  THE  "CHICAGO  RAILROAD  GAZETTE,"  JULY,  1870. 


ENGLISH  AND  AMERICAN  IRON  BRIDGES. 


Some  two  months  ago  tenders  were  solicited  for  the 
construction  of  iron  railway  bridges  of  spans  of  100  and 
200  feet,  by  the  Intercolonial  Railway  of  Canada,  con- 
necting Quebec  and  Halifax.  This  call  was  very  gener- 
ally responded  to,  there  being  tenders  put  in  by  nineteen 
English,  one  Belgian,  and  sixteen  American  bridge- 
builders. 

The  specification,  which  was  a  rigid  one,  called  for 
uniformity  of  strength,  but  left  the  design  open  to  each 
person.  The  bridges  were  all  to  be  of  wrought  iron, 
capable  of  bearing  ly^  gross  tons  per  lineal  foot,  in 
addition  to  their  own  weight,  without  straining  the  iron 
in  tension  to  over  10,000  pounds  per  square  inch.  The 
iron  of  the  200  feet  spans  was  to  be  capable  of  bearing 
60,000  pounds  per  square  inch  before  breaking,  and 
that  of  the  100  feet  spans  50,000  pounds  per  square  inch. 

Much  interest  was  felt  as  to  the  result  of  this  compe- 
tition, which  was  virtually  one  between  English  and 
American  systems  of  bridge  building.  The  decision  was 
that  the  long  spans  were  awarded  to  an  American  firm, 
Messrs.  CLARKE,  REEVES  &  CO.,  of  Phoenix- 
ville.  Pa.,  and  the  short  ^pans  to  English  bridge- 
builders,  the  Fairbairn  Manufacturing  Company,  of 
Manchester.  Of  the  thirty-six  plans  submitted,  only 
three  or  four  were  rejected  on  account  of  not  coming 
up  to  special  strength. 

The  bridges  of  Clarke,  Reeves  &  Co.  were  selected 
for  the  long  spans,  not  only  as  being  undoubtedly  first- 
class,  botli  in  material  and  workmanship,  but  also  as 
being  the  lowest  responsible  tender.  Some  curiosity 
has  been  expressed  to  know  how  .\merican  bridge- 
builders,  using  high-priced  iron,  and  paying  higlier 
wages  for  labor  tlian  their  English  competitors,  could 
yet  build  a  less  costly  bridge. 

While  it  is  to  some  extent  true  that  the  specifications 
allowed  of  a  lower  (juality  and  less  expensive  iron  for 
the  100  than  for  the  200  feet  span,  yet  one  of  the  prin- 
cipal reasons  why  an  American  firm  was  lowest  on  the 
long  and  an  English  firm  on  the  short  spans  is  owing  to 
the  less  weight  of  iron  required  by  the  American  system 
of  bridge,  and  this  is  more  apparent  the  longer  the  span. 
(24) 


Some  persons  erroneously  suppose  that  the  more  iron 
there  is  in  a  bridge  the  stronger  it  will  be.  But  a  little 
reflection  will  show  that  it  is  only  the  iron  that  is 
working,  or,  in  other  words,  that  is  actually  strained  by 
the  load,  that  contributes  to  the  strength  of  the  struc- 
ture. All  the  rest  is  dead  weight,  and  merely  weighs 
down  the  bridge.  In  very  short  spans  this  is  not  dis- 
advantageous, as  it  tends  to  diminish  vibration,  but  in 
long  spans  where  the  weight  of  the  bridge  much  ex- 
ceeds that  of  the  load  passing  over  it,  every  pound  of 
iron  that  does  not  contribute  to  the  strength  of  the 
bridge  is  a  positive  injury.  To  illustrate  this  more 
clearly:  if  one  bridge  weighs  125  tons  and  another 
250,  and  both  are  strained  by  the  rolling  load  10,000 
pounds  per  square  inch,  the  lighter  is  the  stronger  of  the 
two.  But  if  the  125  ton  bridge  be  strained  10,000  pounds 
per  square  inch,  while  the  250  ton  bridge  is  strained 
only  5000  pounds  per  square  inch,  then  the  latter  has 
really  double  the  strength  and  double  the  life  of  the 
former;  for  half  the  iron  may  corrode  away,  and  then 
the  working  area  of  the  bar  will  be  equal.  It  is  not 
clearly  perceiving  this  fact — that  the  strength  of  the 
bridge  depends  upon  the  working  area  of  its  part — 
that  has  led  our  English  friends  to  make  such  heavy 
bridges. 

Ill  several  plans,  if  the  strain  per  square  inch  are 
alike  for  similar  loads  they  must  all  be  of  the  same 
strength,  providing  the  connections  are  equally  perfect. 
Some  lake  more  iron  than  others  to  efl'ect  the  result, 
but  the  result  is  the  same. 

The  lightness  of  American  bridges  is  due — ist,  to  the 
concentration  of  material  along  the  lines  of  strain, 
which  enabled  a  lighter  web  system  to  be  used,  and 
hence  a  higher  truss ;  2d,  to  this  greater  height  of 
truss,  which  throws  less  leverage  on  the  upper  and  lower 
chord  system,  and  hence  recjuires  less  iron  in  their 
members;  3d,  to  the  use  of  eye  and  pin  connections 
instead  of  rivets,  by  which  there  is  no  waste  of  metal 
to  compensate  for  the  deduction  of  rivet-holes. 

American  bridges  are  stiffer  vertically  and  better 
braced  laterally  than  English   bridges,  their  greater 


n 


PHUiNIXVJLLE  BRIDGE-  WORKS. 


height  giving  less  deflecticn  under  a  load,  and  allowing 
of  overhead  bracing  as  well  as  that  below  the  track. 

But  the  less  quantity  of  iron  required  to  do  the  work 
is  not  the  whole  explanation  of  the  less  cost  of  American 
as  compared  with  English  bridges.  A  second  and 
equally  important  reason  is  the  less  amount  of  manual 
labor  required  to  construct  and  erect  them — owing  to 
the  general  use  of  machinery  in  forming  all  the  parts. 

English  bridges  are  made  of  low-price  iron  and  re- 
quire a  great  deal  of  it,  and  a  great  deal  of  h  nd-labor 
in  constructing  and  erecting. 

American  bridges  have  all  their  principal  parts  formed 
by  machinery.  They  are  of  exact  uniform  dimensions, 
in  similar  spans,  and  hence  perfectly  interchangeable, 
like  the  parts  of  the  locks  of  the  American  rifles,  or  of 
sewing-machines.  Hence  machine-labor  can  be  ap- 
plied to  their  manufacture,  and  the  cost  at  the  works 
reduced  to  a  minimum. 

But  American  bridges  have  still  another  advantage. 
They  are  so  made  that  nearly  all  the  work  is  done  at 
the  shops,  and  they  can  be  erected  with  the  least  possible 
amount  of  labor,  and  that  imskilled.  In  fact,  the  cost 
of  erecting  the  staging  is  the  principal  expense ;  after 
that  a  200  feet  span  can  be  erected  and  made  self-sus- 
taininp  in  the  space  of  two  days,  if  necessary.  (See 
letter  of  T.  D.  Lovett,  Ex-Chief  Engineer  Ohio  and 
Mississippi  Railway  Company.) 

But  the  English  bridge  is  only  about  half  done  when 
the  scaffolding  is  built  and  the  iron  placed  upon  it.  It 
has  then  to  be  riveted  together,  which  is  expensive,  as 
the  conveniences  for  such  work  at  the  site  of  a  bridge 
are  not  often  great.  It  is  slow  and  tedious,  requiring 
from  two  to  three  weeks  to  put  together  a  200  feet  span. 

Taking  all  these  things  into  account,  it  will  be  seen 
how  American  bridge-builders  have  been  able  to  com- 
pete with  English  firms  on  the  large  bridge  at  Buffalo, 
and  in  the  recent  case  of  the  long  span  bridges  of  the 
Intercolonial  Railroad  of  Canada. 

Cincinnati,  Nov.  ii,  1S72. 
Gentlemen  : — 

Below  please  find  a  statemert  of  the  force  employed 
and  time  consumed  in  raising  the  last  span  of  Medora 


Bridge  over  White  River,  near  Mtvlora,  Indiana,  foi 
the  Ohio  and  Mississippi  Railway  Company.  Length, 
centre  to  centra  of  end  pins,  147  feet  6  inches.  Height 
of  truss,  28  feet. 

The  force  consisted  of — 

Howard  and  ten  men,  one  truss. 

Buzby  and  ten  men,  one  truss. 

Kelly  and  ten  men,  running  in  iron. 

Bussing  and  seven  men,  connecting  top  end  of  tie 
bars,  afternoon  only.  Employed  on  oth-r  work  not 
connected  with  raising  in  the  forenoon. 

Monday,  February  5,  1872,  coivmienced  running  in 
iron  at  8  a.m.,  at  5.30  p.m.,  same  day,  span  swinging 
clear  and  top  laterals  on.  Iron  moved  on  an  average 
one  hundred  and  fifty  feet.  The  men  all  went  to 
Medora  for  dinner,  one  and  a  half  miles  distant,  which 
consumed  one  hour  strong,  making  the  actual  working 
time  eight  hours  and  thirty  minutes.  Total  force,  three 
foremen  and  thirty  men  full  time,  one  foreman  and 
seven  men  four  and  a  half  hours,  equivalent  to  three 
hundred  and  sixteen  and  a  half  hours  for  one  man. 

Style  of  truss,  "  Pratt  or  Whipple."  Details  of  con- 
struction by  Clarke,  Reeves  &  Co.,  by  whom  the 
bridge  was  constructed  at  their  works  in  Phcenixville, 
Pennsylvania. 

E.  S.  Duval,  Superintendent  of  Bridges,  Ohio  and 
Mississippi  Railway,  says:  — 

"I  am  satisfied  that  the  same  length  with  the  same 
crew  of  men  can  be  raised  in  less  time  than  last  span 
at  Medora.  We  had  no  idea  of  swinging  the  span  that 
day.  We  commenced  in  the  morning;  after  dinner, 
however,  seeing  how  rapidly  we  had  advanced  in  the 
fore  part  of  the  day,  we  then  determined  to  swing  the 
span  before  leaving  it." 

Many  of  the  men  had  been  in  the  employ  of  the 
Ohio  and  Mississippi  Company  under  my  directions 
for  a  number  of  years. 

You  are  at  liberty  to  use  the  above  in  any  manner 
you  see  proi)er. 

Very  truly  yours, 

Thos.  D.  Lovett, 

Ex-  Chief  Eng;incer  Ohio  and  Mississippi  Railway  Co. 


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8-^"- 

60(U  "    204-1"^  17     "  6481    "        8.5  "  1,350  "    825,000"    88,285    "   ,35,191    "   .    " 


"This  Column  after  having  ui'en  crippled,  was  again  subjected  m>  pressure,  and  in  this  crippled  state,  failed  under   a    total    pressure  of   156,000  lbs.,  or 
26,712  lbs.  per  ^    inch. 


holes. 


li.ength  of  Column  proper,  J3'ii"— Radius  of  senti-spheric  Ca?iiings,  5',"— making  length  over  all,  24^o'\ 
i'rhis  Column  had  thirtv-five  0- (6'' 


9(6"°  punched  holes  8  "  apart  in  each  of  .•  opposite  Segments,  and  yielded  in  the  dire(flion  of  a  plane  through  the  punched 


-^^MMswwwinipwiw 


^'  '-'WP'JVWillt''; 


